Difference between revisions of "Soaps and Detergents" - New World Encyclopedia

From New World Encyclopedia
 
(22 intermediate revisions by 8 users not shown)
Line 1: Line 1:
−
{{Claimed}}
+
{{Images OK}}{{Submitted}}{{Approved}}{{Paid}}{{Copyedited}}
−
{{Otheruses}}
+
[[Image:Decorative_Soaps.jpg|thumb|300px|right|A collection of decorative soaps.]]
−
[[Image:Decorative_Soaps.jpg|thumb|300px|right|A collection of decorative soaps typically found in hotel rooms.]]
 
−
[[Image:a bar of soap.jpg|thumb|200px|Soap most commonly appears in bar form. This particular bar has seen some use and has lost its "bar" shape.]]
 
  
−
A '''detergent''' is a [[chemical compound]] or mixture of compounds used as a [[cleaning]] agent. A '''soap''' is a cleaning agent that is composed of one or more [[salt]]s of [[fatty acid]]s. In this sense, ''detergent'' is an umbrella term that includes soaps and other cleaning agents that differ in chemical composition. Even plain water, when used for cleaning, may be called a detergent.
+
A '''detergent''' is a [[chemical compound]] or mixture of compounds used as a [[cleaning]] agent. A '''soap''' is a cleaning agent that is composed of one or more [[salt]]s of [[fatty acid]]s. Thus, by its broad definition, ''detergent'' is an umbrella term that includes soaps and other cleaning agents with various chemical compositions. Often, however, the term ''detergent'' is used in a narrower sense to refer to synthetic cleaning agents that are not soaps (that is, not salts of fatty acids). Conversely, the term ''soap'' is often used in a broader sense to include a variety of cleaning agents (such as "laundry soap"). Here, the term ''detergent'' will be used in its broader sense (to include soaps), and the term ''soap'' will be used for products that consist mainly of fatty acid salts.
−
 
 
−
There are, however, alternate ways in which the terms ''detergent'' and ''soap'' are used. For instance, the word ''detergent'' is often used when referring to synthetic cleaning agents that are not soaps (that is, not salts of fatty acids). Also, the word ''soap'' is applied to cleaning materials (such as "laundry soap") that do not contain salts of fatty acids. Most kinds of "soap" in use today are actually synthetic detergents, which are less expensive, more effective, and easier to manufacture.
 
−
 
 
−
 
 
−
* While effort has been made to reduce their negative effect upon the environment, the results have been mixed.
 
−
 
 
−
The term is often used to differentiate between soap and other chemical [[surfactant]]s used for cleaning purposes. Sometimes the word "detergent" is used in distinction to "soap."
 
−
 
 
−
'''Soap''' is a [[surfactant]] used in conjunction with [[water]] for washing and [[cleaning]].
 
−
 
 
−
==Terminology for soaps and detergents==
 
−
 
 
−
For a while during the infancy of other surfactants as commercial detergent products, the term "syndet," short for "synthetic detergent" was promoted to indicate this, but never caught on very well, and is incorrect in any event because soap is itself synthesized via [[saponification]] of [[glyceride]]s. The term "soapless soap" also saw a brief vogue.  Unfortunately there is no accurate term for detergents not made of soap other than "soapless detergent" or "non-soap detergent."
 
−
 
 
−
Also, the term "detergent" is sometimes used for [[surfactant]]s in general, even when they are not used for cleaning.  As can be seen above, this too is terminology that should be avoided as long as the term "surfactant" itself is available.
 
−
 
 
−
Probably the most widely used detergents other than water are soaps or mixtures composed chiefly of soaps.  However, not all soaps have significant detergency.
 
  
 +
Detergents are commonly used in products for personal hygiene, dishwashing, and laundry. They are also used as ingredients in antiseptic agents, dry-cleaning solutions, lubricating [[oil]]s, and [[gasoline]].
 +
{{toc}}
 +
Although detergents are very useful, the excessive use of certain ingredients has led to adverse effects on the environment. For instance, [[phosphate]] additives used for [[water softener]]s led to an increase in phosphorus content in lakes and rivers, triggering [[algal bloom]]s that in turn consumed most of the [[oxygen]] in the waters, killing fish and plants. Efforts have been made to reduce such negative effects, but the results have been mixed.
  
 
== History ==
 
== History ==
Line 30: Line 14:
 
The earliest known use of a natural, soap-like material was the powder of nuts from the [[Sapindus|Reeta (Sapindus)]] tree, a powder used by Indians since antiquity. In accordance with [[Ayurveda|Ayurvedic]] teachings, Hindus in India were obliged to bathe at least once a day, every morning.
 
The earliest known use of a natural, soap-like material was the powder of nuts from the [[Sapindus|Reeta (Sapindus)]] tree, a powder used by Indians since antiquity. In accordance with [[Ayurveda|Ayurvedic]] teachings, Hindus in India were obliged to bathe at least once a day, every morning.
  
−
The [[Babylonia]]ns used clay cylinders containing a soap-like substance, dating from 2800 BCE. A formula for soap—consisting of water, [[alkali]], and [[cassia]] oil—was written on a Babylonian clay tablet around 2200 BCE.
+
The [[Babylonia]]ns used clay cylinders containing a soap-like substance, dating from 2800 B.C.E. A formula for soap—consisting of water, [[alkali]], and [[cassia]] [[oil]]—was written on a Babylonian clay tablet around 2200 B.C.E.
  
−
The [[Ebers papyrus]] (Egypt, 1550 BCE) indicates that [[ancient Egypt]]ians bathed regularly and combined animal and vegetable oils with alkaline salts to create a soap-like substance. Egyptian documents mention that a soap-like substance was used in the preparation of [[wool]] for weaving.
+
The [[Ebers papyrus]] (Egypt, 1550 B.C.E.) indicates that [[ancient Egypt]]ians bathed regularly and combined animal and vegetable oils with alkaline salts to create a soap-like substance. Egyptian documents mention that a soap-like substance was used in the preparation of [[wool]] for weaving.
  
 
===Roman History===
 
===Roman History===
−
 
+
It has been reported that a factory producing soap-like substances was found in the ruins of [[Pompeii]] (C.E. 79). However, this report appears to be a misinterpretation of the survival of some soapy mineral substance, probably soapstone, at the [[Fullonica]] where it was used for dressing recently cleansed textiles. The ancient Romans were generally ignorant of soap's detergent properties and made use of the [[strigil]] to scrape dirt and sweat from the body.
−
It has been reported that a factory producing soap-like substances was found in the ruins of [[Pompeii]] (CE 79). However, this report appears to be a misinterpretation of the survival of some soapy mineral substance, probably soapstone, at the [[Fullonica]] where it was used for dressing recently cleansed textiles. The ancient Romans were generally ignorant of soap's detergent properties and made use of the [[strigil]] to scrape dirt and sweat from the body.
 
  
 
The word "soap" (Latin ''sapo'') appears first in a European language in [[Pliny the Elder]]'s ''[[Natural History (Pliny)|Historia Naturalis]]'', which discusses the manufacture of soap from [[tallow]] and ashes, but the only use he mentions for it is as a [[pomade]] for hair. He mentions rather disapprovingly that among the [[Gaul]]s and [[Teuton|Germans]], men are likelier to use it than women.<ref>[[Pliny the Elder]], ''[[Natural History (Pliny)|Natural History]]'', [http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/28*.html#191 XXVIII.191]. Retrieved November 14, 2007.</ref>
 
The word "soap" (Latin ''sapo'') appears first in a European language in [[Pliny the Elder]]'s ''[[Natural History (Pliny)|Historia Naturalis]]'', which discusses the manufacture of soap from [[tallow]] and ashes, but the only use he mentions for it is as a [[pomade]] for hair. He mentions rather disapprovingly that among the [[Gaul]]s and [[Teuton|Germans]], men are likelier to use it than women.<ref>[[Pliny the Elder]], ''[[Natural History (Pliny)|Natural History]]'', [http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/28*.html#191 XXVIII.191]. Retrieved November 14, 2007.</ref>
  
−
According to one legend, "soap" takes its name from a "[[Mount Sapo]]" where [[Ancient Rome|ancient Romans]] [[sacrifice|sacrificed]] animals. Rain would send a mix of animal tallow and wood ash down the mountain and into the clay soil on the banks of the [[Tiber]]. Eventually, women noticed that it was easier to clean clothes with this "soap." The location of Mount Sapo is unknown, as is the source of the "ancient Roman legend" to which this tale is typically credited.<ref>[http://www.algebralab.org/passage/passage.aspx?file=Chemistry_Soaps.xml] </ref>
+
According to one legend, "soap" takes its name from a "[[Mount Sapo]]" where [[Ancient Rome|ancient Romans]] [[sacrifice|sacrificed]] [[animal]]s. [[Rain]] would send a mix of animal tallow and wood ash down the mountain and into the clay soil on the banks of the [[Tiber]]. Eventually, women noticed that it was easier to clean clothes with this "soap." The location of Mount Sapo is unknown, as is the source of the "ancient Roman legend" to which this tale is typically credited.<ref>[http://www.algebralab.org/passage/passage.aspx?file=Chemistry_Soaps.xml Soaps and Detergents]. Algebra Lab. Retrieved November 17, 2007.</ref>
  
 
In fact, the [[Latin]] word ''sapo'' simply means "soap." Borrowed from a Celtic or Germanic language, the term is [[cognate]] with the Latin term ''sebum'' (meaning "tallow"), which appears in Pliny the Elder's account. Roman animal sacrifices usually burned only the bones and inedible entrails of the sacrificed animals; edible meat and fat from the sacrifices were taken by humans. Under such circumstances, animal sacrifices would not have included enough fat to make much soap. The legend about Mount Sapo is probably apocryphal.
 
In fact, the [[Latin]] word ''sapo'' simply means "soap." Borrowed from a Celtic or Germanic language, the term is [[cognate]] with the Latin term ''sebum'' (meaning "tallow"), which appears in Pliny the Elder's account. Roman animal sacrifices usually burned only the bones and inedible entrails of the sacrificed animals; edible meat and fat from the sacrifices were taken by humans. Under such circumstances, animal sacrifices would not have included enough fat to make much soap. The legend about Mount Sapo is probably apocryphal.
  
−
===Muslim History===
+
===Middle East===
 +
A twelfth-century Islamic document describes the process of soap production.<ref>Jim Al-Khalili, ''Science and Islam'' Part 2, BBC Productions. </ref> It mentions the key ingredient, [[alkali]], which later becomes crucial to modern chemistry, derived from ''al-qaly'' or "ashes".
  
−
True soaps made from vegetable oils (such as [[olive oil]]), aromatic oils (such as [[thyme]] oil), and lye (''al-Soda al-Kawia'', or [[sodium hydroxide]]), were first produced by [[Alchemy (Islam)|Muslim chemists]] in the [[Islamic Golden Age|medieval Islamic world]].<ref>[[Ahmad Y Hassan]], [http://www.history-science-technology.com/Articles/articles%2072.htm  Technology Transfer in the Chemical Industries].</ref> From the beginning of the seventh century, soap was produced in Nablus (West Bank, Palestine), Kufa (Iraq) and Basra (Iraq). Soaps as we know them today are descendants of historical Arabian soaps.
+
By the thirteenth century, the manufacture of soap in the Islamic world had become virtually industrialized, with sources in [[Nablus]], [[Fes]], [[Damascus]], and [[Aleppo]].<ref>Michael Phillips, [http://imeu.org/article/nablus-olive-oil-soap-a-palestinian-tradition-lives-on Nablus' olive oil soap: a Palestinian tradition lives on] Institute for Middle East Understanding (IMEU), March 11, 2008. Retrieved October 14, 2015.</ref>
  
−
Arabian soaps were perfumed and colored; some were liquid, others were hard. The Arabs also had special soap for shaving. It was commercially sold for 3 Dirhams (0.3 [[Dinars]]) a piece in CE 981. The [[Persian people|Persian]] chemist [[Al-Razi]] wrote a manuscript on recipes for true soap. A recently discovered manuscript from the thirteenth century details more recipes for soap making. One recipe recommends taking some sesame oil, a sprinkle of potash, alkali and some lime, mixing them together, and boiling. When cooked, they are poured into molds and left to set, leaving hard soap.
+
=== Medieval Europe===
 +
Soapmakers in [[Naples]] were members of a [[guild]] in the late sixth century (then under the control of the [[Eastern Roman Empire]]),<ref>Harald Kleinschmidt, ''Understanding the Middle Ages: The Transformation of Ideas and Attitudes in the Medieval world'' (Boydell & Brewer, 2000, ISBN 085115770X). </ref> and in the eighth century, soap-making was well known in Italy and Spain.<ref>Raymond G. Bistline, Jr., "Anionic and Related Lime Soap Dispersants," in ''Anionic surfactants: organic chemistry'', Helmut Stache, (ed.) (CRC Press, 1996, ISBN 0824793943).</ref> The lands of [[Medieval Spain]] were a leading soapmaker by 800, and soapmaking began in the [[Kingdom of England]] about 1200.<ref>[http://www.soap-flakes.com/history.html History of Soap Flakes]. Retrieved October 14, 2015.</ref>
  
−
Historically, soap was made by mixing [[animal fat]]s with [[lye]]. Because of the [[caustic]] nature of lye, this was a dangerous procedure, which could result in serious [[chemical burn]]s or even [[blindness]]. Before the commercial production of lye became commonplace, it was produced at home for soap making from the ashes of a hardwood fire.
+
[[Castile soap]], made from [[olive oil]], was produced in Europe as early as the sixteenth century.
  
 
===Modern History===
 
===Modern History===
−
[[Image:Palmolive soap 1922 advertisement ladies home journal.jpeg|thumb|200px|right|1922 magazine advertisement for Palmolive soap.]]
 
  
−
[[Castile soap]], made from [[olive oil]], was produced in Europe as early as the sixteenth century.
+
In modern times, the use of soap has become universal in industrialized nations due to a better understanding of the role of [[hygiene]] in reducing the population size of [[pathogenic]] [[microorganism]]s. Manufactured bar soaps first became available in the late nineteenth century, and [[advertising]] campaigns in Europe and the United States helped to increase popular awareness of the relationship between cleanliness and health. By the 1950s, soap had gained public acceptance as an instrument of personal hygiene.
−
 
 
−
In modern times, the use of soap has become universal in industrialized nations due to a better understanding of the role of [[hygiene]] in reducing the population size of [[pathogenic]] [[microorganism]]s. Manufactured bar soaps first became available in the late nineteenth century, and [[advertising]] campaigns in Europe and the United States helped to increase popular awareness of the relationship between cleanliness and health. By the 1950s, soap had gained public acceptance as an instrument of [[hygiene|personal hygiene]].
 
  
 
[[Image:Azul e Branco.JPG|220px|thumb|A bar of blue-white offenbach soap.]]
 
[[Image:Azul e Branco.JPG|220px|thumb|A bar of blue-white offenbach soap.]]
  
 
===Commercial soap production===
 
===Commercial soap production===
−
 
 
Until the [[Industrial Revolution]], soap-making was done on a small scale and the product was rough. In 1789, [[Andrew Pears]] started making a high-quality, transparent soap in [[London]]. He and his grandson, Francis Pears, opened a factory in [[Isleworth]] in 1862. [[William Gossage]] produced low-priced, good quality soap from the 1850s. [[Robert Spear Hudson (soap)|Robert Spear Hudson]] began manufacturing a soap powder in 1837, initially by grinding the soap with a mortar and pestle. [[William Hesketh Lever]] and his brother James bought a small soap works in [[Warrington]] in 1885 and founded what became one of the largest soap businesses, now called [[Unilever]]. These soap businesses were among the first to employ large-scale [[advertising]] campaigns to sell the output of their factories.
 
Until the [[Industrial Revolution]], soap-making was done on a small scale and the product was rough. In 1789, [[Andrew Pears]] started making a high-quality, transparent soap in [[London]]. He and his grandson, Francis Pears, opened a factory in [[Isleworth]] in 1862. [[William Gossage]] produced low-priced, good quality soap from the 1850s. [[Robert Spear Hudson (soap)|Robert Spear Hudson]] began manufacturing a soap powder in 1837, initially by grinding the soap with a mortar and pestle. [[William Hesketh Lever]] and his brother James bought a small soap works in [[Warrington]] in 1885 and founded what became one of the largest soap businesses, now called [[Unilever]]. These soap businesses were among the first to employ large-scale [[advertising]] campaigns to sell the output of their factories.
−
 
−
 
−
8888888888
 
−
 
−
Col. Enc:
 
−
"Soap is a cleansing agent. It cleanses by lowering the surface tension of water, by emulsifying grease, and by absorbing dirt into the foam. ... Chemically, soaps are metallic salts of fatty acids. The manufacture of soap is based on a chemical reaction (saponification) in which an alkali acts upon a fat to form a metal salt (soap) and an alcohol (glycerol)."
 
−
 
−
"A detergent is substance that aids in the removal of dirt. Detergents act mainly on the oily films that trap dirt particles. The detergent molecules have a hydrocarbon portion, soluble in oil, and an ionic portion, soluble in water. The detergent acts as an emulsifier, i.e., by bridging the water and oil phases, it breaks the oil into tiny droplets suspended in water. The disruption of the oil film allows the dirt particles to become solubilized. Soap, the sodium salt of long-chain fatty acids, is a good detergent although it has some disadvantages, e.g., it forms insoluble compounds with certain salts found in hard water thus diminishing its effectiveness, and in acid solutions, frequently used in industry, it is decomposed (thus precipitating the free fatty acid of the soap). Synthetic detergents were first developed for commercial use in the 1950s. Detergents are classified as anionic, or negatively charged, e.g., soaps; cationic, or positively charged, e.g., tetraalkyl ammonium chloride, used as fabric softeners; nonionic, e.g., certain esters made from oil, used as degreasing agents in industry; and zwitterionic, containing both positive and negative ions on the same molecule. Detergents are incorporated in such products as dry-cleaning solutions, toothpastes, antiseptics, and solutions for removing poison sprays from vegetables and fruit."
 
−
 
−
EB:
 
−
 
−
Soap and detergent:
 
−
"Soap and detergent are substances that, when dissolved in water, possess the ability to remove dirt from surfaces such as the human skin, textiles, and other solids."
 
−
 
−
Soap:
 
−
"Any of a group of organic compounds that are salts of fatty acids, usually stearic acid (with 18 carbon atoms) or palmitic acid (with 16 carbon atoms). The source may be any vegetable oil or animal fat. Soaps are emulsifying agents commonly used for cleaning; they have long been made from lye and fat. Detergents are entirely synthetic and may or may not be soaps. Soaps of metals heavier than sodium are not very soluble; the curdy precipitate made by soap in hard water is the calcium or magnesium salt of the fatty acid in the soap. Heavy-metal soaps are used in lubricating greases, as gel thickeners, and in paints. Napalm is an aluminum soap."
 
−
 
−
Detergent:
 
−
"Any of various surfactants (substances that reduce surface tension) used to dislodge dirt from soiled surfaces and retain it in suspension, allowing it to be rinsed away. The term usually refers to synthetic substances and excludes soaps. The characteristic features of a molecule of any detergent are a hydrophilic (water-attracting) end and a hydrophobic (oil-attracting) end. In ionic detergents, the hydrophilic property is conferred by the ionized part of the molecule. In nonionic detergents, hydrophilicity is based on the presence of multiple hydroxyl groups or other hydrophilic groups. Besides those used in water to clean dishes and laundry, detergents that function in other solvents are used in lubricating oils, gasolines, and dry-cleaning solvents to prevent or remove unwanted deposits. They are also used as emulsifying agents (see emulsion)."
 
−
 
−
Detergent:
 
−
"any of various surface-active agents (surfactants) particularly effective in dislodging foreign matter from soiled surfaces and retaining it in suspension. The term usually denotes a synthetic substance that is not prepared by saponifying fats and oils (as is soap). Dishwashing and laundering of clothing are the principal applications of detergents."
 
−
 
−
88888888888
 
  
 
== Forms of soap ==
 
== Forms of soap ==
−
 
 
Soap usually comes in a solid, [[molding (process)|mold]]ed form, called a ''bar'', based on its typical shape. The use of thick [[liquid]] soap has also become widespread, especially from [[soap dispenser]]s in public [[washroom]]s. When applied to a soiled surface, soapy water effectively holds particles in suspension, which can then be rinsed off with clean water.
 
Soap usually comes in a solid, [[molding (process)|mold]]ed form, called a ''bar'', based on its typical shape. The use of thick [[liquid]] soap has also become widespread, especially from [[soap dispenser]]s in public [[washroom]]s. When applied to a soiled surface, soapy water effectively holds particles in suspension, which can then be rinsed off with clean water.
  
−
==How soap works==
+
==Components of detergents and their functions==
−
[[Image:Soapfunction1.jpg|thumb|right|200px|Diagram of how soap works.]]
+
As noted above, soaps are salts of fatty acids. A molecule of soap may be represented as follows:
−
 
 
−
As noted above, soaps are salts of fatty acids. Consequently, each molecule of soap has (a) an ionic end, which is soluble in water (a [[polar]] substance); and (b) a [[nonpolar]] hydrocarbon chain that can attach to nonpolar materials such as [[fat|grease]] and [[oil]]. A molecule of soap may be represented as follows:
 
 
::::(fatty end)  :CH<sub>3</sub>-(CH<sub>2</sub>)<sub>n</sub> - COO<sup>&minus;</sup>Na<sup>+</sup>:  (water soluble end)
 
::::(fatty end)  :CH<sub>3</sub>-(CH<sub>2</sub>)<sub>n</sub> - COO<sup>&minus;</sup>Na<sup>+</sup>:  (water soluble end)
  
−
When soapy water is applied to a soiled surface, the hydrocarbon ("fatty") portions of the soap molecules attach to dirt and oils, while the ionic ends of the molecules keep them soluble in water. In this manner, the soap molecules act as "handles" that make it easier to rinse the grease and dirt away with clean water. In other words, matter that is normally insoluble in water is removed by [[emulsification]].
+
Thus, each molecule of soap has (a) an ionic end, which is hydrophilic (water-attracting) and soluble in water; and (b) a [[nonpolar]] hydrocarbon chain that is hydrophobic (water-repelling) that can attach to nonpolar materials such as [[fat|grease]] and [[oil]]. These molecules form bridges between water and oil, breaking up the oil and forming an emulsion consisting of oil droplets suspended in water. Substances made up of such molecules are called '''[[surfactant]]s'''. They reduce the [[surface tension]] of water, and they reduce interfacial tension between oil and water by adsorbing at the liquid-liquid interface.
 +
[[Image:Soapfunction1.jpg|thumb|right|250px|Diagram of how soap works.]]
 +
Surfactants are key components of detergents in general. Because of their presence in detergents, oil and associated dirt particles become solubilized and can be rinsed away with clean water.
  
−
==Composition of detergents==
+
Many types of [[organic compound]]s can function as surfactants. They (and the detergents that contain them) are often classified into four groups: anionic, cationic, zwitterionic (with plus and minus charges), and non-ionic. In the case of non-ionic surfactants, the hydrophilic nature of one end is conferred by the presence of special functional groups such as hydroxyl groups. Most brands of laundry detergent have anionic or nonionic surfactants or a mixture of the two, although cationic surfactants have also been used. The use of cationic and anionic surfactants together is incompatible in the same detergent. The usual content of surfactants in a typical detergent is about 8-18 percent.
−
[[Image:Washingpowder.jpg|thumb|[[Laundry detergent]]s are one of many possible uses of detergents.]]
 
  
−
Detergents, especially those made for use with water, are mixtures of various components that serve different functions.<ref>[http://www.detergents.in/ Detergents.] Retrieved November 14, 2007.</ref> A given detergent may contain several of the following components:
+
In addition to surfactants, detergents various other components that serve different functions. A given detergent may contain several of the following components:
  
−
* [[Surfactant]]s, which 'cut' [[grease]] from surfaces.
 
 
* [[Abrasive]]s that scour the surfaces.
 
* [[Abrasive]]s that scour the surfaces.
−
* Substances that modify [[pH]] or affect performance or stability of other ingredients—for example, [[acids]] for [[descaling]], or [[caustics]] to destroy dirt.
+
* Substances that modify or control [[pH]], or affect the performance or stability of other ingredients. For example, [[acids]] may be used for [[descaling]], or [[caustics]] to destroy dirt.
−
* [[Water softener]]s counteract the effect of "hardness" ions in other components.
+
* [[Water softener]]s counteract the effect of "hardness" ions (particularly [[calcium]] and [[magnesium]] ions). Some form of [[sodium]] [[phosphate]] (such as [[trisodium orthophosphate]], [[monosodium orthophosphate]], or a [[tripolyphosphate]]) can be used here. In some locations, phosphate is no longer used due to environmental concerns, as phosphates in surface waters stimulate [[algal bloom]]. As alternatives, other [[chelating agent]]s or [[ion exchange]] materials are used.
−
* [[Oxidizing agent]]s (oxidizers) that [[bleach]] surfaces and destroy dirt.
+
* [[Oxidizing agent]]s (oxidizers) that [[bleach]] surfaces and destroy dirt. In [[North America]], [[sodium hypochlorite]] based bleach additives are more common. These work at lower temperatures and do not need activation. In [[Europe]], [[peroxide]]-based bleaches are prevalent.
 +
* Fillers, forming a bulk component in many laundry detergents, modify the physical properties of the material. In solid detergents, [[sodium sulfate]] or [[borax]] can be used to make the powder free-flowing. In liquid detergents, [[alcohol]]s are added to increase the solubility of the compounds and to lower the mixture's freezing point.
 
* Non-surfactant materials that keep dirt in [[suspension (chemistry)|suspension]].
 
* Non-surfactant materials that keep dirt in [[suspension (chemistry)|suspension]].
−
* [[Enzyme]]s to digest [[protein]]s, [[fat]]s, or [[carbohydrate]]s in dirt or to modify fabric feel.
+
* [[Enzyme]]s that digest [[protein]]s, [[fat]]s, or [[carbohydrate]]s. They help remove biological stains (such as stains from grass or blood). Enzymes produced by the [[bacteria]] ''[[Bacillus subtilis]]'' and ''[[Bacillus licheniformis]]'' are often used.
 
* Ingredients that modify the [[foam]]ing properties of the cleaning surfactants, to either [[foaming agent|stabilize]] or [[anti-foaming agent|counteract]] foam.
 
* Ingredients that modify the [[foam]]ing properties of the cleaning surfactants, to either [[foaming agent|stabilize]] or [[anti-foaming agent|counteract]] foam.
−
* Additional ingredients, such as [[optical brightener]]s, softeners, colors, and [[perfume]]s.
+
* Additional ingredients include [[optical brightener]]s, fabric softeners, colors, and [[perfume]]s.
  
 
The material to be cleaned dictates the composition of the detergent that should be used and the apparatus to be used. For instance, the following are examples of different glass-cleaning agents that are appropriate for different contexts:
 
The material to be cleaned dictates the composition of the detergent that should be used and the apparatus to be used. For instance, the following are examples of different glass-cleaning agents that are appropriate for different contexts:
Line 123: Line 78:
 
* [[Windshield]] washer fluid is useful especially when a vehicle is in motion.
 
* [[Windshield]] washer fluid is useful especially when a vehicle is in motion.
  
 +
==Soap making==
 +
[[Image:Soap P1140887.jpg|thumb|200px|Handmade soaps sold at a shop in [[Hyères]], [[France]].]]
  
−
===Contents===
+
Some individuals continue to make soap in the home. The traditional name "[[soaper]]," for a soap maker, is still used by those who make soap as a [[hobby]]. Those who make their own soaps are also known as soap crafters.
  
−
Detergent molecules are long and the detergents can mold into different forms of matter so  it can be asymmetrical: one end attracts long pieces of  dirt while the other end attracts water, which is why detergent lifts dirt from wet clothes. Detergent molecules come in two forms, straight and branched - a difference that affects sudsing but not cleansing ability.  The suds of the straight molecules of detergent break down quickly, while the suds of branched molecules break down slowly if at all.
+
The most popular process for handmade soaps today is the cold process, where oils such as [[olive oil]] are reacted with [[lye]]. Some soap makers use the "melt and pour" process, where a pre-made soap base is melted and poured into individual molds. Some [[soaper]]s also practice other processes, such as the historical hot process, and make special soaps such as clear soap ([[glycerin soap]]).
  
−
A key ingredient in both solid and liquid laundry detergents is a [[surfactant]]. A surfactant is a substance which, when added to water, significantly reduces the [[surface tension]] of the water.  This effect allows water to wash surfaces better. There are many different types of [[organic compound]]s which can function as surfactants.  Surfactants are thick, viscous liquids; however, some are soft, waxy or greasy solids.
+
===Use of fats and oils ===
 +
[[Image:Savon de Marseille.jpg|thumb|200px|Handicraft made [[Marseille soap]].]]
  
−
Surfactants typically have somewhat longer [[molecule]]s which may or may not have an [[electric charge]].  Surfactants with uncharged molecules are '''non-ionic surfactant'''s. Surfactants with positively charged molecules (or ions) are '''cationic surfactant'''s.  Surfactants with negatively charged molecules (or ions) are '''anionic surfactant'''s. Surfactants with both positively and negatively charged part in the same molecule are '''zwitterionic surfactants'''. Most brands of laundry detergent have anionic or nonionic surfactants or a mixture of the two, although cationic surfactants have been used in laundry detergents.  The use of cationic and anionic surfactants together is incompatible in the same detergent. The usual content of surfactants in a typical detergent is about 8-18%.
+
Soap is derived from either [[oil]]s or [[fat]]s. ''[[Sodium tallowate]]'', a common ingredient in many soaps, is derived from [[Kitchen rendering|rendered]] [[beef]] fat. Soap can also be made of vegetable oils, such as [[palm oil]], and the product is typically softer.
  
−
In powdered or granular solid detergents, the surfactant is soaked into the solid ingredients.  In liquid laundry detergents, liquid or even solid surfactant are blended into the liquid detergent.  There is usually a limit on how much liquid surfactant can soak into powder or granular solids solid detergent mushy.  More liquid surfactant can usually be blended into a liquid detergent.  The liquid detergents commonly contain at least some water to help liquefy the other additives and still have the detergent pour able.  The liquid detergents may also have other [[solvent]] liquids, such as [[alcohol]] or a [[hydrotrope]], to help blend all the additives together.
+
An array of quality oils and [[butter]]s are used in the process, such as [[olive]], [[coconut]], palm, [[cocoa]] butter, [[hemp oil]] and shea butter. Each oil chosen by the soap maker has unique characteristics that provide different qualities to handmade soaps including mildness, lathering and hardness. For example, olive oil provides mildness in soap; coconut oil provides lots of lather while coconut and palm oils provides hardness. Most common, though, is a combination of coconut, palm, and olive oils.
  
−
Laundry detergents may have ingredients to help control the [[pH]] of the wash water.  For example, solid detergents usually contain [[sodium carbonate]] (soda ash) or [[sodium bicarbonate]] to maintain [[pH]] by neutralizing any [[acidic]] materials that may enter the wash water.
+
If soap is made from pure [[olive oil]] it may be called [[Castile soap]] or [[Marseille soap]]. The term "Castile soap" is also sometimes applied to soaps with a mix of oils, but a high percentage of olive oil.
  
−
Compounds called "builders" are often used to enhance ("build") the surfactant effect. Their role is to lower the [[water hardness]] by scavenging the [[calcium]] and [[magnesium]] ions and adsorbing them or chelating them. Some form of [[sodium]] [[phosphate]] can be used here, such as [[trisodium orthophosphate]], [[monosodium orthophosphate]], or a form of [[tripolyphosphate]] (TPP). In some locations, phosphate is no longer used as an additive due to environmental concerns as phosphates in surface waters stimulate [[algal bloom]]. As alternatives, other [[chelating agent]]s are used. Sodium carbonate precipitates insoluble [[calcium carbonate]] and [[magnesium carbonate]]. Organic chemicals similar to [[EDTA]] can be employed, eg. [[nitriloacetic acid]] (NTA). [[Borate]]s can be used as well. [[Ion exchange]] materials are frequently used in modern formulations; the most common kind is based on synthetic [[zeolite]]s, often with [[polycarboxylate]] based [[polyelectrolyte]]s. The usual content of such materials in a typical detergent is about 20-45%.
+
===Reactions with alkali===
 +
When [[fat]] (or [[oil]]) is reacted with lye ([[sodium hydroxide]]), the product is a hard soap. When fat is reacted with [[potassium hydroxide]], the product is a soap that is either soft or liquid. Either reaction is known as ''[[saponification]]''. The fat is [[Hydrolysis|hydrolyzed]] by the alkali, yielding [[glycerol]] and crude soap. Historically, the [[alkali]] used was potassium hydroxide, made from the deliberate burning of vegetation such as [[bracken]], or from wood ashes.
  
−
Many detergents contain [[bleach]]es. In North American countries, [[sodium hypochlorite]] based bleach additives are more common. These work at lower temperatures and do not need activation. In Europe, [[peroxide]]-based bleaches are prevalent instead. The chemicals employed are usually [[sodium percarbonate]] and [[sodium perborate]], or other compounds that release [[hydrogen peroxide]]. Peroxide bleaches either need higher temperature (60 °C or more) to become effective, or a suitable [[catalyst]] or activator (eg. [[manganese]] or [[iron]] complexes, or [[tetraacetylethylenediamine|TAED]]) which lowers the required temperature down to 40 °C or even to [[room temperature]]. The usual content of bleaches in a typical detergent is about 15-30%. It is possible to overdo the bleaching; the [[Persil Power]] fiasco is a good example of deployment of too powerful bleaching activator.
+
=== Cold and hot processes ===
  
−
The detergents promising making the laundry "whiter than white" usually contain [[optical brightener]]s, acting as [[phosphor]]s converting some [[ultraviolet]] radiation to blue light and optically offsetting the yellowing of the material. The usual content of optical brighteners in a typical detergent is about 0.1%.
+
;Hot process
  
−
Fillers are a bulk component in many detergents. Their primary role is modifying the physical properties of the material. In solid detergents, [[sodium sulfate]] or [[borax]] can be used to make the powder free-flowing. In liquid detergents [[alcohol]]s are added to increase the solubility of the compounds and to lower the mixture's freezing point. [[Corrosion inhibitor]]s can be added to prolong the lifetime of the washing machines; [[sodium silicate]] can be used here. [[Anti-foaming agent]]s are added to lower the production of [[foam]] and to make the presence of detergents in [[wastewater]] less obvious. The usual content of fillers in a typical detergent is about 5-45%.
+
In the hot-process method, [[lye]] and [[fatty acid|fat]] are boiled together at 80&ndash;100°[[Celsius|C]] until saponification occurs. After saponification, the soap is sometimes [[precipitation (chemistry)|precipitated]] from the solution by adding salt, and the excess liquid drained off. The hot, soft soap is then spooned into a mold.
  
−
Some laundry detergents have [[enzyme]]s to help in removal of biological stains (eg. grass or blood), often enzymes produced by the bacteria ''[[Bacillus subtilis]]'' and ''[[Bacillus licheniformis]]''. The content of enzymes can reach up to 0.75%.  
+
The hot-process method was used when the purity of lye was unreliable, and when naturally produced lye, such as [[potash]], was used. The main benefit of hot processing is that the exact concentration of the lye solution does not need to be known to perform the process with adequate success.
  
−
Some laundry detergents have [[fabric softener]]s. [[Perfume]] or color ingredients are sometimes added for better smell or to give a detergent some color. 
+
Unlike cold-processed soap, hot-processed soap can be used right away because lye and fat saponify more quickly at the higher temperatures used in hot-process soap making.
  
−
Other brands, however, are left without these additives, marketed to those who avoid these because of [[allergy|allergies]] or individual preference.  There are also detergents made with [[vegetable]]-based surfactants which are popular in [[health food]] stores.
+
;Cold process
−
 
 
−
==Soapmaking==
 
−
[[Image:Soap P1140887.jpg|thumb|Handmade soaps sold at a shop in [[Hyères]], [[France]]]]
 
−
The most popular soapmaking processes today is the cold process method, where fats such as [[olive oil]] react with [[Sodium Hydroxide|lye]]. Soapmakers sometimes use the [[melt and pour]] process, where a premade soap base is melted and poured in individual molds.  While some people think that this is not really soap-''making'', the Hand Crafted Soap Makers Guild does recognize this as a legitimate form of soap making or soap crafting. Some [[soaper]]s also practice other processes, such as the historical hot process, and make special soaps such as clear soap ([[glycerin soap]]), which must be made through the melt and pour process.
 
−
 
 
−
Handmade soap differs from industrial soap in that, usually, an excess of fat is sometimes used to consume the alkali (''superfatting''), and in that the [[glycerin]] is not removed. Superfatted soap, soap which contains excess fat, is more skin-friendly than industrial soap; though, if not properly formulated, it can leave users with a "greasy" feel to their skin.  Often, [[emollient]]s such as [[jojoba]] oil or [[shea butter]] are added 'at trace' (the point at which the [[saponification]] process is sufficiently advanced that the soap has begun to thicken), after most of the oils have saponified, so that they remain unreacted in the finished soap.  Superfatting can also be accomplished through a processed called superfat discount, where, instead of putting in extra fats, the soap maker puts in less lye.
 
−
 
 
−
===Lye===
 
−
Reacting fat with [[sodium hydroxide]] will produce a hard soap.
 
−
 
 
−
Reacting fat with [[potassium hydroxide]] will produce a soap that is either soft or liquid. Historically, the alkali used was [[potassium hydroxide]] made from the deliberate burning of vegetation such as [[bracken]], or from wood ashes.
 
−
 
 
−
===Fat===
 
−
[[Image:Savon de Marseille.jpg|thumb|200px|Handicraft made [[Marseille soap]]]]
 
−
Soap is derived from either oils or fats. ''[[Sodium tallowate]]'', a common ingredient in many soaps, is in fact derived from [[Kitchen rendering|rendered]] beef fat. Soap can also be made of vegetable oils, such as [[palm oil]], and the product is typically softer. If soap is made from pure [[olive oil]] it may be called [[Castile soap]] or [[Marseille soap]]. Castile is also sometimes applied to soaps with a mix of oils, but a high percentage of olive oil.
 
−
 
 
−
An array of quality oils and butters are used in the process  such as olive, coconut, palm,  cocoa butter, [[hemp oil]] and shea butter to list a few. Each oil chosen by the soap maker has unique characteristics that provide different qualities to handmade soaps including mildness, lathering and hardness.  For example olive oil provides mildness in soap; coconut oil provides lots of lather while coconut and palm oils provides hardness.  Most common, though, is a combination of coconut, palm, and olive oils.
 
−
 
 
−
===Process===
 
−
In both cold-process and hot-process soapmaking, heat may be required for [[saponification]].
 
−
 
 
−
Cold-process soapmaking takes place at a temperature sufficiently above room temperature to ensure the [[melting|liquification]] of the fat being used, and requires that the lye and fat be kept warm after mixing to ensure that the soap is completely saponified.
 
  
−
Unlike cold-processed soap, hot-processed soap can be used right away because lye and fat saponify more quickly at the higher temperatures used in hot-process soapmaking.
+
In the cold-process method, fats such as [[olive oil]] are reacted with [[Sodium Hydroxide|lye]], at a temperature that is sufficiently above room temperature to ensure the [[melting|liquefaction]] of the fat being used. It requires that the lye and fat be kept warm after mixing to ensure that the soap is completely saponified.
  
−
Hot-process was used when the purity of lye was unreliable, and can use natural lye solutions such as [[potash]]. The main benefit of hot processing is that the exact concentration of the lye solution does not need to be known to perform the process with adequate success.
+
The cold process requires exact measurement of lye to fat using saponification charts, to ensure that the finished product is mild and skin friendly. Excess unreacted lye in the soap will result in a very high [[pH]] and can burn or irritate skin. Not enough lye, and the soap is greasy and oily. Most soap makers formulate their recipes with a 4-10 percent discount of lye so that all of the lye is reacted and that excess fat is left for skin conditioning benefits. (Saponification charts can also be used in hot-process soap making, but are not as necessary as for the cold-process method.)
  
−
Cold-process requires exact measurement of lye to fat using saponification charts to ensure that the finished product is mild and skin friendly. Saponification charts can also be used in hot-process soapmaking, but are not as necessary as in cold-process.
+
The lye is dissolved in water. Then oils are heated, or melted if they are solid at room temperature. Once both substances have cooled to approximately 100-110°[[Fahrenheit|F]], and are no more than 10 degrees Fahrenheit apart in temperature, they may be combined. This lye-fat mixture is stirred until it reaches a stage called "trace"—the point at which the saponification process is sufficiently advanced that the soap has begun to thicken. (Modern-day amateur soap makers often use a stick blender to speed this process.). There are varying levels of trace: light, medium, and heavy.
  
−
;Hot process
+
[[Essential oil]]s, [[fragrance oil]]s, botanicals, herbs, [[oat]]meal or other additives are added at light trace, just as the mixture starts to thicken. The batch is then poured into molds, kept warm with towels or blankets, and left to continue saponification for 18 to 48 hours.
−
In the hot-process method, lye and [[fatty acid|fat]] are boiled together at 80 &ndash; 100 °C until saponification occurs, which the soapmaker can determine by taste (the bright, distinctive taste of lye disappears once all the lye is saponified) or by eye (the experienced eye can tell when gel stage and full saponification have occurred).
 
  
−
After saponification has occurred, the soap is sometimes [[precipitation (chemistry)|precipitated]] from the solution by adding salt, and the excess liquid drained off.
+
After the insulation period, the soap is firm enough to be removed from the mold and cut into bars. At this time, it is safe to use the soap since saponification is complete. However, cold-process soaps are typically cured and hardened on a drying rack for 2-6 weeks (depending on initial water content) before use.
−
 
 
−
The hot, soft soap is then spooned into a mold.
 
−
 
 
−
;Cold process
 
−
A cold-process soapmaker first looks up the saponification value of the fats being used on a saponification chart, which is then used to calculate the appropriate amount of lye. Excess unreacted lye in the soap will result in a very high pH and can burn or irritate skin. Not enough lye, and the soap is greasy and oily. Most soap makers formulate their recipes with a 4-10% discount of lye so that all of the lye is reacted and that excess fat is left for skin conditioning benefits.
 
−
 
 
−
The lye is dissolved in water.  Then oils are heated, or melted if they are solid at room temperature.  Once both substances have cooled to approximately 100-110 degrees Fahrenheit, and are no more than 10 degrees Fahrenheit apart in temperature, they may be combined.  This lye-fat mixture is stirred until "trace"(Modern-day amateur soapmakers often use a stick blender to speed this process.).  There are varying levels of trace.  Depending on how your additives will affect trace, they may be added at light trace, medium trace or heavy trace.  After much stirring, the mixture turns to the consistency of a thin pudding.
 
−
 
 
−
[[Essential oil]]s, [[fragrance oil]]s, botanicals, herbs, oatmeal or other additives are added at light trace, just as the mixture starts to thicken.
 
−
 
 
−
The batch is then poured into molds, kept warm with towels or blankets, and left to continue saponification for 18 to 48 hours. Milk soaps are the exception. They do not require insulation. Insulation may cause the milk to burn. During this time, it is normal for the soap to go through a "gel phase" where the opaque soap will turn somewhat transparent for several hours before turning opaque again. The soap will continue to give off heat for many hours after trace.
 
−
 
 
−
After the insulation period the soap is firm enough to be removed from the mold and cut into bars. At this time, it is safe to use the soap since saponification is complete. However, cold-process soaps are typically cured and hardened on a drying rack for 2-6 weeks (depending on initial water content) before use.  If using caustic soda it is recommended that the soap is left to cure for at least 4 weeks.
 
  
 
===Purification and finishing===
 
===Purification and finishing===
Line 201: Line 124:
 
Most of the water is then removed from the soap. This was traditionally done on a chill roll which produced the soap flakes commonly used in the 1940s and 1950s. This process was superseded by spray dryers and then by vacuum dryers.  
 
Most of the water is then removed from the soap. This was traditionally done on a chill roll which produced the soap flakes commonly used in the 1940s and 1950s. This process was superseded by spray dryers and then by vacuum dryers.  
  
−
The dry soap (approximately 6-12% moisture) is then compacted into small pellets. These pellets are now ready for soap finishing, the process of converting raw soap pellets into a salable product, usually bars.
+
The dry soap (approximately 6-12 percent moisture) is then compacted into small pellets. These pellets are now ready for soap finishing, the process of converting raw soap pellets into a salable product, usually bars.
  
 
Soap pellets are combined with fragrances and other materials and blended to homogeneity in an amalgamator (mixer). The mass is then discharged from the mixer into a refiner which, by means of an [[auger]], forces the soap through a fine wire screen. From the refiner the soap passes over a roller mill (French milling or hard milling) in a manner similar to [[calendering]] paper or plastic or to making [[chocolate liquor]]. The soap is then passed through one or more additional refiners to further plasticize the soap mass. Immediately before extrusion it passes through a vacuum chamber to remove any entrapped air. It is then extruded into a long log or blank, cut to convenient lengths, passed through a metal detector and then stamped into shape in refrigerated tools. The pressed bars are packaged in many ways.
 
Soap pellets are combined with fragrances and other materials and blended to homogeneity in an amalgamator (mixer). The mass is then discharged from the mixer into a refiner which, by means of an [[auger]], forces the soap through a fine wire screen. From the refiner the soap passes over a roller mill (French milling or hard milling) in a manner similar to [[calendering]] paper or plastic or to making [[chocolate liquor]]. The soap is then passed through one or more additional refiners to further plasticize the soap mass. Immediately before extrusion it passes through a vacuum chamber to remove any entrapped air. It is then extruded into a long log or blank, cut to convenient lengths, passed through a metal detector and then stamped into shape in refrigerated tools. The pressed bars are packaged in many ways.
  
 
[[Sand]] or [[pumice]] may be added to produce a [[wiktionary:scouring|scouring]] soap. This process is most common in creating soaps used for human hygiene. The scouring agents serve to remove dead skin cells from the surface being cleaned. This process is called [[exfoliation (cosmetology)|exfoliation]]. Many newer materials are used for exfoliating soaps which are effective but do not have the sharp edges and poor size distribution of pumice.
 
[[Sand]] or [[pumice]] may be added to produce a [[wiktionary:scouring|scouring]] soap. This process is most common in creating soaps used for human hygiene. The scouring agents serve to remove dead skin cells from the surface being cleaned. This process is called [[exfoliation (cosmetology)|exfoliation]]. Many newer materials are used for exfoliating soaps which are effective but do not have the sharp edges and poor size distribution of pumice.
−
 
−
== Soap manufacture ==
 
−
 
−
Many soaps are mixtures of [[sodium]] ([[soda]]) or [[potassium]] ([[potash]]) [[salt]]s of [[fatty acid]]s. They can be prepared by reacting oils or fats with an [[alkali]] (such as [[sodium hydroxide|sodium]] or [[potassium hydroxide]]) at 80&ndash;100 °C. The process is known as ''[[saponification]]''. The fats are [[Hydrolysis|hydrolyzed]] by the base, yielding [[glycerol]] and crude soap. Historically, the alkali used was potassium hydroxide made from the deliberate burning of vegetation such as [[bracken]], or from wood ashes.
 
−
 
−
A common ingredient in many soaps is ''sodium tallowate'', which is derived from [[Kitchen rendering|rendered]] beef fat. Soap can also be made from vegetable oils, such as [[olive oil]]. Soap made entirely (or mostly) from olive oil is called [[castile soap]].
 
−
 
−
===Soap purification and finishing===
 
−
 
−
The common process of purifying soap involves removal of [[sodium chloride]], [[sodium hydroxide]], and [[glycerol]]. These impurities are removed by [[boiling]] the crude soap [[curd]]s in water and re-precipitating the soap with salt.
 
−
 
−
Most of the water is then removed from the soap. This was traditionally done on a chill roll which produced the soap flakes commonly used in the 1940s and 1950s. This process was superseded by spray dryers and then by vacuum dryers.
 
−
 
−
The dry soap (approximately 6-12% moisture) is then compacted into small pellets. These pellets are now ready for soap finishing. Soap finishing is the process of converting raw soap pellets into salable product, usually bars.
 
−
 
−
Soap pellets are combined with fragrances and other materials and blended to homogeneity in an amalgamator (mixer). The mass is then discharged from the mixer into a refiner which, by means of an auger, forces the soap through a fine wire screen. From the refiner the soap passes over a roller mill (French milling or hard milling) in a manner similar to [[calendering]] paper or plastic or to making [[chocolate liquor]]. The soap is then passed through one or more additional refiners to further plasticize the soap mass. Immediately before extrusion it passes through a vacuum chamber to remove any entrapped air. It is then extruded into a long log or blank, cut to convenient lengths, passed through a metal detector and then stamped into shape in refrigerated tools. The pressed bars are packaged in many ways.
 
−
 
−
[[Sand]] or [[pumice]] may be added to produce a [[wiktionary:scouring|scouring]] soap. This process is most common in creating soaps used for human hygiene. The scouring agents serve to remove dead skin cells from the surface being cleaned. This process is called [[exfoliation (cosmetology)|exfoliation]]. Many newer materials are used for exfoliating soaps which are effective but do not have the sharp edges and pore size distribution of pumice.
 
  
 
==Uses==
 
==Uses==
 +
Detergents are mainly used in products for personal hygiene, dishwashing, and laundry. In addition, detergents are often added to a variety of products, to prevent the buildup of undesirable deposits. Some products that may contain detergents include:
 +
* [[toothpaste]]s
 +
* antiseptic agents
 +
* dry-cleaning solutions
 +
* [[gasoline]]
 +
* lubricating [[oil]]s
  
−
[Soaps are useful for cleansing because soap [[molecule]]s attach readily to both [[nonpolar]] molecules (such as [[fat|grease]] or [[oil]]) and polar molecules (such as [[water]]). Although grease will normally adhere to skin or clothing, the soap molecules can attach to it as a "handle" and make it easier to rinse away.] Allowing soap to sit on any surface (such as skin or clothes) over time can imbalance the moisture content on it and result in the dissolving of fabrics and dryness of skin.
+
A nature-friendly way of interrupting an ant trail is to pour soapy water on the trail. The soapy water destroys the scent the ants were following to get to food.
−
 
 
−
Soap water can be used as a nature friendly way to get rid of an ant problem in your food. By pouring soap water on an ant trail it destroys the ant's sense of smell and the scent the ants were following to get to the food.
 
−
 
 
−
==Handmade soap==
 
−
[[Image:Handmade soap.jpg|thumb|Handmade soap.]]
 
−
 
 
−
Some individuals continue to make soap in the home.  The traditional name "[[soaper]]," for a soapmaker, is still used by those who make soap as a [[hobby]]. Those who make their own soaps are also known as soapcrafters.
 
−
 
 
−
The most popular soapmaking processes today is the [[cold process]] method, where fats such as [[olive oil]] react with [[lye]]. Soapmakers sometimes use the [[melt and pour]] process, where a premade soap base is melted and poured in individual molds, but this is not really to be considered soap-''making''. Some [[soaper]]s also practice other processes, such as the historical [[hot process]], and make special soaps such as clear soap (aka [[glycerin soap]]).
 
−
 
 
−
Handmade soap differs from industrial soap in that, usually, an excess of fat is used to consume the alkali ''(superfatting)'', and in that the [[glycerin]] is not removed. Superfatted soap, soap which contains excess fat, is more skin-friendly than industrial soap; though, if not properly formulated, it can leave users with a "greasy" feel to their skin.  Often, [[emollient]]s such as [[jojoba]] oil or [[shea butter]] are added 'at trace' (the point at which the saponification process is sufficiently advanced that the soap has begun to thicken), after most of the oils have [[saponification|saponified]], so that they remain unreacted in the finished soap.
 
  
 
==Disadvantages==
 
==Disadvantages==
−
Today, fat-based soaps have mostly been superseded by modern [[detergent]]s. Washing agents do not contain soap for cleaning fabric, but for reducing foam.
+
Today, [[fat]]-based soaps have mostly been superseded by modern [[detergent]]s. Washing agents do not contain soap for cleaning fabric, but for reducing foam.
  
 
The disadvantages of commercial soaps are:
 
The disadvantages of commercial soaps are:
−
*Due to the fact that most commercial soaps eliminate the glycerine from soaps to use in other industires, this deprives the [[skin]] of the natural, moisturising glycerine and generally leaves the skin feeling dry.
+
*Due to the fact that most commercial soaps eliminate the [[glycerine]] from soaps to use in other industries, this deprives the [[skin]] of the natural, moisturising glycerine and generally leaves the skin feeling dry.
−
*Some antibacterial soaps have chemicals killing bacteria that coexist on the skin's surface and are essential to skin health. More alarmingly, the rise of antibacterial soaps contributes to [[antibiotic resistant]] bacteria. {{fact}}
+
*Some antibacterial soaps have chemicals killing [[bacteria]] that coexist on the skin's surface and are essential to skin health.  
−
*Soap-based products often contain the additive [[sodium laureth sulfate]], which research has found to be harsh on skin. This product is also present in many non-soap cleaners for personal hygiene (shampoos, bathfoams, toothpaste, etc.).
+
*Soap-based products often contain the additive [[sodium laureth sulfate]], which research has found to be harsh on skin. This product is also present in many non-soap cleaners for personal hygiene (such as shampoos, bathfoams, [[toothpaste]]).
 
*Soap can react mildly [[Base (chemistry)|basically]] with fabrics resulting in damage over the long term. This is usually due to excess [[sodium]] [[hydroxide]] ([[sodium hydroxide|NaOH]], an [[alkali]]/base) left from manufacture, but can also be caused by the very slight presence of NaOH from the [[equilibrium reaction]]:<br/>R-COO-Na + H<sub>2</sub>O ↔ R-COO<sup>-</sup> + Na<sup>+</sup> + H<sub>2</sub>O ↔ R-COOH + NaOH <br/>However, this equilibrium strongly favors the left-hand side so the fraction of NaOH formed is minuscule
 
*Soap can react mildly [[Base (chemistry)|basically]] with fabrics resulting in damage over the long term. This is usually due to excess [[sodium]] [[hydroxide]] ([[sodium hydroxide|NaOH]], an [[alkali]]/base) left from manufacture, but can also be caused by the very slight presence of NaOH from the [[equilibrium reaction]]:<br/>R-COO-Na + H<sub>2</sub>O ↔ R-COO<sup>-</sup> + Na<sup>+</sup> + H<sub>2</sub>O ↔ R-COOH + NaOH <br/>However, this equilibrium strongly favors the left-hand side so the fraction of NaOH formed is minuscule
 
*Soap reacts with [[Lime (mineral)|lime]] to form an insoluble deposit (soap scum) in "[[Water Hardness|hard water]]":<br/>2Na<sup>+</sup>(R-COO)<sup>-</sup><sub>(aq)</sub> + Ca<sup>2+</sup>(HCO<sub>3</sub><sup>-</sup>)<sub>2</sub><sub>(aq)</sub> → 2Na<sup>+</sup>(HCO<sub>3</sub>)<sup>-</sup><sub>(aq)</sub> + Ca(R-COO)<sub>2</sub><sub>(s)</sub> - where R stands for an [[alkyl]] group (precipitate)
 
*Soap reacts with [[Lime (mineral)|lime]] to form an insoluble deposit (soap scum) in "[[Water Hardness|hard water]]":<br/>2Na<sup>+</sup>(R-COO)<sup>-</sup><sub>(aq)</sub> + Ca<sup>2+</sup>(HCO<sub>3</sub><sup>-</sup>)<sub>2</sub><sub>(aq)</sub> → 2Na<sup>+</sup>(HCO<sub>3</sub>)<sup>-</sup><sub>(aq)</sub> + Ca(R-COO)<sub>2</sub><sub>(s)</sub> - where R stands for an [[alkyl]] group (precipitate)
−
*A wide variety of [[emollient]] materials, such as [[shea]] or [[cocoa butter]]s, are [[substantive]] to the [[skin]].
 
 
*Poorly finished soaps contain [[alkali]] ([[sodium hydroxide|NaOH]]) and react mildly [[Base (chemistry)|basically]] with skin and fabric; commercial products are finished to neutrality or to a weak [[acid]] content to prevent this and be more compatible with the [[skin|skin's]] slightly [[acidic]] [[pH]].
 
*Poorly finished soaps contain [[alkali]] ([[sodium hydroxide|NaOH]]) and react mildly [[Base (chemistry)|basically]] with skin and fabric; commercial products are finished to neutrality or to a weak [[acid]] content to prevent this and be more compatible with the [[skin|skin's]] slightly [[acidic]] [[pH]].
−
*Commercial products use [[chelation|chelating]] molecules ([[sequestrant]]s), often [[EDTA]] derivatives to bind with any free {{Calcium}} or {{Magnesium}} ions and prevent [[soap scum]]. These also help reduce fragrance loss, discolouration and [[Rancidification|rancidity]].
+
*Commercial products use [[chelation|chelating]] molecules ([[sequestrant]]s), often [[EDTA]] derivatives to bind with any free {{Calcium}} or {{Magnesium}} ions and prevent [[soap scum]]. These also help reduce fragrance loss, discoloration. and [[Rancidification|rancidity]].
−
*Castile soap has a very high alkalinity level, measured at about 9. pH of skin and hair has a slightly acidic pH level known to be about 5 to 6. Due to the high pH level, liquid castile soap is usually not recommended by soapmakers who market this high pH soap for washing hair because it is not pH-balanced and it may cause hair to become dry.
+
*Castile soap has a very high alkalinity level, measured at about 9. [[pH]] of skin and hair has a slightly acidic pH level known to be about 5 to 6. Due to the high pH level, liquid castile soap is usually not recommended by soapmakers who market this high pH soap for washing hair because it is not pH-balanced and it may cause hair to become dry.
  
 
== Environmental concerns ==
 
== Environmental concerns ==
−
 
+
In the 1960s, detergent manufacturers waged an advertising battle over who had the longest lasting suds, and detergent compounds quickly appeared in the waterways. Suds began to appear in streams, rivers, and lakes. At the foot of the [[Niagara Falls]], piles of discolored detergent foam rose eight feet high.
−
In the 1960s, detergent manufacturers waged an advertising battle over who had the longest lasting suds, and detergent compounds quickly appeared in the waterways. Suds began to appear in streams, rivers, lakes, and at the foot of [[Niagara Falls]], piles of discolored detergent foam rose eight feet high.
 
  
 
Detergents also contain phosphate additives to soften the water and thereby improve the effectiveness of the detergent molecules. It was noted that between 1940 and 1970 the amount of [[phosphates]] in city wastewater increased from 20,000 to 150,000 tons per year.
 
Detergents also contain phosphate additives to soften the water and thereby improve the effectiveness of the detergent molecules. It was noted that between 1940 and 1970 the amount of [[phosphates]] in city wastewater increased from 20,000 to 150,000 tons per year.
  
−
With the increase in phosphates, [[algal blooms]] grew splendidly on the excess phosphorus and consumed the majority of all oxygen in the waters, killing fish and plants.
+
With the increase in phosphates, [[algal blooms]] grew splendidly on the excess [[phosphorus]] and consumed the majority of all oxygen in the waters, killing fish and plants.
  
−
== Laundry detergents ==
+
Allowing a detergent to sit on any surface (such as skin or clothes) over time can cause an imbalance in [[pH]] and moisture content on the surface, damaging the fabric and injuring the skin.
−
 
 
−
'''Laundry detergent''' is a type of [[detergent]] that is added when one is washing [[laundry]] to help get the laundry cleaner.  It is often colloquially called '''laundry soap''' or simply '''detergent''' or '''soap''' and it helps wash the fabric in a manner rather analogous to the way [[soap]] helps wash hands, other parts of the body, or other things cleaner than washing with [[water]] alone.  Laundry detergent has traditionally been a [[powder]]ed or granular [[solid]], but the use of [[liquid]] laundry detergents has gradually increased over the years, and these days use of liquid detergent equals or even exceeds use of solid detergent.  Some brands also manufacture laundry soap in tablets and dissolvable packets, so as to eliminate the need to measure soap for each load of laundry.
 
−
 
 
−
===Use of laundry detergent===
 
−
 
 
−
Because it is consumed when it is used, the sale of laundry detergent is a rather large business.  There are many different kinds or [[brand]]s of laundry detergent sold, many of them claiming some special qualities as selling points.  Each brand has its own [[instructions]] on how to use it and what amount to use written on the [[container]] it comes in.  Some brands of laundry detergent purport to be more [[concentration|concentrated]] and can be added in smaller amounts.  The detergent can be added onto the laundry or to the wash water at the start of the wash, or it can be added beforehand or soon after starting the wash into a special compartment in a [[washing machine]] made for that purpose, to be flushed into the wash by the wash water.  Often [[bleach]] is a separate additive to the wash, but there are laundry detergents which have bleach already blended in with them.  The detergent is [[soluble]] in water and makes the water wash the laundry better along with agitation or tumbling.  The detergent does its work and is needed during the initial "Wash" cycle to separate the dirt or soil out from the fabric.  The purpose of the rinses which follow is to rinse the detergent residue from the laundry as well as to remove the dirt suspended in the wash water by replacing the initial wash water with fresh water.
 
−
 
 
−
Separate stain pre-treatment products are sometimes available to be added directly to stained areas of fabrics.  However, undiluted liquid laundry detergent or a paste of solid detergent made by mixing in a little water may be used to pre-treat heavily soiled or stained areas of the fabric by scrubbing in the detergent prior to the wash.  Removal of certain types of stains is tough and can be achieved only with varying degrees of success. Also, special [[oxidizer]] washing products have become available in liquid or solid granular form.  Such solid products often contain [[sodium percarbonate]] or [[sodium perborate]] and the liquid products often contain [[hydrogen peroxide]].  They are often marketed as containing "[[active oxygen]]." Some laundry detergent is specially sold for [[wool]] fabric.
 
−
 
 
−
===Containers and sizes===
 
−
 
 
−
Solid laundry detergent is commonly sold in [[cardboard]] boxes and plastic tubs.  In many parts of Africa, laundry detergent is also sold in single-use packets. The size of the boxes can vary from small single-use boxes sold from [[vending machine]]s in [[laundromat]]s to large economy-size boxes.  In some cases, plastic measuring scoops have been included inside the boxes.  Liquid detergent is sold in [[plastic]] bottles, usually [[high density polyethylene]] or sometimes [[polyethylene terephtalate|PET]] or other kinds.  Again, various sizes are available.  On large size bottles, a handle to carry the bottle is often pre-formed as part of the bottle.  The bottle caps are often made large enough so they can be used as cups for measuring out the liquid detergent.
 
−
 
 
−
===Contents===
 
−
 
 
−
A key ingredient in both solid and liquid laundry detergents is a [[surfactant]].  A surfactant is a substance which, when added to water, significantly reduces the [[surface tension]] of the water.  This effect allows water to wash surfaces better.  There are many different types of [[organic compound]]s which can function as surfactants.  Most surfactants are thick, viscous liquids, but some are soft, waxy or greasy solids.
 
−
Detergent Molecules consist of:
 
−
           
 
−
 
 
−
Surfactants typically have somewhat longer [[molecule]]s which may or may not have an [[electric charge]].  Surfactants with uncharged molecules are '''non-ionic surfactant'''s.  Surfactants with positively charged molecules (or ions) are '''cationic surfactant'''s.  Surfactants with negatively charged molecules (or ions) are '''anionic surfactant'''s. Surfactants with both positively and negatively charged part in the same molecule are '''zwitterionic surfactants'''. Most brands of laundry detergent have anionic or nonionic surfactants or a mixture of the two, although cationic surfactants have been used in laundry detergents.  The use of cationic and anionic surfactants together is incompatible in the same detergent. 
 
−
 
 
−
In powdered or granular solid detergents, the surfactant is soaked into the solid ingredients.  In liquid laundry detergents, liquid or even solid surfactant are blended into the liquid detergent.  There is usually a limit on how much liquid surfactant can soak into powder or granular solids before making the solid detergent mushy.  More liquid surfactant can usually be blended into a liquid detergent.  The liquid detergents commonly contain at least some water to help liquify the other additives and still have the detergent pourable.  The liquid detergents may also have other [[solvent]] liquids, such as [[alcohol]] or a [[hydrotrope]], to help blend all the additives together. 
 
−
 
 
−
Laundry detergents may have ingredients to help control the [[pH]] of the wash water.  For example, solid detergents usually contain [[sodium carbonate]] (soda ash) or [[sodium bicarbonate]] to maintain pH by neutralizing any [[acidic]] materials that may enter the wash water.  Some other ingredients which solid detergents may have include [[sodium silicate]] or some form of [[sodium]] [[phosphate]] such as [[trisodium orthophosphate]], [[monosodium orthophosphate]], or a form of [[tripolyphosphate]].  In some locations, phosphate is no longer used as an additive due to environmental concerns. 
 
−
 
 
−
Some laundry detergents have [[enzyme]]s to help in stain removal.  Some laundry detergents have [[fabric softener]]s.  [[Perfume]] or color ingredients are sometimes added for better smell or to give a detergent some color. 
 
−
 
 
−
Other brands, however, are left without these additives, marketed to those who avoid these because of allergies or individual preference.  There are also detergents made with [[vegetable]]-based surfactants which are popular in health food stores.
 
  
 
==See also==
 
==See also==
−
 
+
* [[Dry cleaning]]
 
* [[Fatty acid]]
 
* [[Fatty acid]]
 
* [[Phosphate]]
 
* [[Phosphate]]
 
* [[Potassium hydroxide]]
 
* [[Potassium hydroxide]]
 
* [[Sodium hydroxide]]
 
* [[Sodium hydroxide]]
 +
* [[Water]]
  
 
== Notes ==
 
== Notes ==
Line 303: Line 174:
  
 
==References==
 
==References==
−
 
+
* Broze, Guy, (ed.). ''Handbook of Detergents, Part A: Properties''. Surfactant Science Series. New York: M. Dekker, 1999. ISBN 0824714172.
−
* Garzena, Patrizia - Tadiello, Marina (2004). Soap Naturally - Ingredients, methods and recipes for natural handmade soap. Programmer Publishing. ISBN 978-0975676400.
+
* Garzena, Patrizia, and Marina Tadiello. ''Soap Naturally: Ingredients, Methods and Recipes for Natural Handmade Soap.'' Mayfield, N.S.W.: Programmer, 2004. ISBN 0975676407.
−
 
+
* Kleinschmidt, Harald. ''Understanding the Middle Ages: The Transformation of Ideas and Attitudes in the Medieval world''. Boydell & Brewer, 2000. ISBN 085115770X.
−
* Maine, Sandy (1995). The Soap Book: Simple Herbal Recipes. Interweave Press. ISBN 1-883010-14-4.
+
* Lange, K. Robert. ''Surfactants: A Practical Handbook.'' Munich: Hanser Publishers, 1999. ISBN 1569902704.
−
 
+
* Maine, Sandy. ''The Soap Book: Simple Herbal Recipes.'' Loveland: Interweave Press, 1995. ISBN 1883010144.
−
* Tarekh Al-Masoudi\the first book. [The Masoudi History-printed in 1989 Beirut-Lebanon]
+
* Stache, Helmut (ed.). ''Anionic surfactants: organic chemistry''. CRC Press, 1996. ISBN 0824793943.
 +
* Urban, David G. ''How to Formulate & Compound Industrial Detergents''. BookSurge Publishing, 2003. ISBN 1588988686.
  
 
==External links==
 
==External links==
−
===History===
+
All links retrieved January 30, 2023.
−
*[http://www.sdahq.org/cleaning/history/ Soap history by The Soap and Detergent Association]
+
*[http://www.alcasoft.com/soapfact/historycontent.html Colonial Soap Making. Its History and Techniques] ''The Soap Factory''
−
*[http://www.butser.org.uk/iafsoap_hcc.html The Discovery and Prehistory of Soap by R W Hedge at Butser Ancient Farm]
+
*[http://www.ccnphawaii.com/glossary.htm Glossary for the Modern Soap Maker. Soap making terminology defined].  
−
*[http://www.cetrange.com/history_soap.html The History of Soap by C'etrange]
+
*[http://www.soapguild.org/ Handcrafted Soap and Cosmetic Guild].  
−
*[http://www.pharmj.com/Editorial/19991218/articles/soap.html History of soap by the Pharmaceutical Journal]
 
−
*[http://www.alcasoft.com/soapfact/historycontent.html Colonial Soap Making. Its History and Techniques. (The Soap Factory)]
 
−
*[http://soapnaturally.org/soaphistory.html Soap Naturally] by Patrizia Garzena, contains a history of soap; rebuts the "Mount Sapo" legend.
 
−
 
 
−
===Soap making===
 
−
 
 
−
*[http://candleandsoap.about.com About Candle and Soap Making] - Soap making projects, instructions, recipes, suppliers and more from About.com
 
−
*[http://www.ccnphawaii.com/glossary.htm Glossary for the Modern Soap Maker. Soap making terminology defined.]
 
−
*[http://www.createthedream.com/ Create The Dream Magazine] - Magazine for Artisans of Soap, Candle, and Herbal Products.
 
−
*[http://www.creativeartisans.org/ Creative Artisans Network.]
 
−
*[http://waltonfeed.com/old/soaphome.html The Soap Making Home Page]
 
−
*[http://www.soapguild.org/ Handcrafted Soap Maker's Guild]
 
−
*[http://www.craftbits.com/viewCategory.do?categoryID=SOA Soap Making Instructions & Recipes]
 
−
*[http://www.mommamuse.com/2006/02/17/instructions-for-making-crock-pot-handmade-soap/ Instructions for Making Crock Pot Handmade Soap]
 
  
−
===Other===
 
  
−
* [http://www.executive-shaving.co.uk/shaving-soaps-shave-soap.php How to Use Shaving Soap]
 
−
* [http://www.mrscleannw.com/tips/soap-scum.html  Removing soap scum]
 
−
* [http://www.freepatentsonline.com/6472364.html Detergent compositions or components]
 
  
 
[[Category:Physical sciences]]
 
[[Category:Physical sciences]]

Latest revision as of 21:42, 30 January 2023

A collection of decorative soaps.

A detergent is a chemical compound or mixture of compounds used as a cleaning agent. A soap is a cleaning agent that is composed of one or more salts of fatty acids. Thus, by its broad definition, detergent is an umbrella term that includes soaps and other cleaning agents with various chemical compositions. Often, however, the term detergent is used in a narrower sense to refer to synthetic cleaning agents that are not soaps (that is, not salts of fatty acids). Conversely, the term soap is often used in a broader sense to include a variety of cleaning agents (such as "laundry soap"). Here, the term detergent will be used in its broader sense (to include soaps), and the term soap will be used for products that consist mainly of fatty acid salts.

Detergents are commonly used in products for personal hygiene, dishwashing, and laundry. They are also used as ingredients in antiseptic agents, dry-cleaning solutions, lubricating oils, and gasoline.

Although detergents are very useful, the excessive use of certain ingredients has led to adverse effects on the environment. For instance, phosphate additives used for water softeners led to an increase in phosphorus content in lakes and rivers, triggering algal blooms that in turn consumed most of the oxygen in the waters, killing fish and plants. Efforts have been made to reduce such negative effects, but the results have been mixed.

History

Early History

Soapnut (Reeta/Sapindus) tree.

The earliest known use of a natural, soap-like material was the powder of nuts from the Reeta (Sapindus) tree, a powder used by Indians since antiquity. In accordance with Ayurvedic teachings, Hindus in India were obliged to bathe at least once a day, every morning.

The Babylonians used clay cylinders containing a soap-like substance, dating from 2800 B.C.E. A formula for soap—consisting of water, alkali, and cassia oil—was written on a Babylonian clay tablet around 2200 B.C.E.

The Ebers papyrus (Egypt, 1550 B.C.E.) indicates that ancient Egyptians bathed regularly and combined animal and vegetable oils with alkaline salts to create a soap-like substance. Egyptian documents mention that a soap-like substance was used in the preparation of wool for weaving.

Roman History

It has been reported that a factory producing soap-like substances was found in the ruins of Pompeii (C.E. 79). However, this report appears to be a misinterpretation of the survival of some soapy mineral substance, probably soapstone, at the Fullonica where it was used for dressing recently cleansed textiles. The ancient Romans were generally ignorant of soap's detergent properties and made use of the strigil to scrape dirt and sweat from the body.

The word "soap" (Latin sapo) appears first in a European language in Pliny the Elder's Historia Naturalis, which discusses the manufacture of soap from tallow and ashes, but the only use he mentions for it is as a pomade for hair. He mentions rather disapprovingly that among the Gauls and Germans, men are likelier to use it than women.[1]

According to one legend, "soap" takes its name from a "Mount Sapo" where ancient Romans sacrificed animals. Rain would send a mix of animal tallow and wood ash down the mountain and into the clay soil on the banks of the Tiber. Eventually, women noticed that it was easier to clean clothes with this "soap." The location of Mount Sapo is unknown, as is the source of the "ancient Roman legend" to which this tale is typically credited.[2]

In fact, the Latin word sapo simply means "soap." Borrowed from a Celtic or Germanic language, the term is cognate with the Latin term sebum (meaning "tallow"), which appears in Pliny the Elder's account. Roman animal sacrifices usually burned only the bones and inedible entrails of the sacrificed animals; edible meat and fat from the sacrifices were taken by humans. Under such circumstances, animal sacrifices would not have included enough fat to make much soap. The legend about Mount Sapo is probably apocryphal.

Middle East

A twelfth-century Islamic document describes the process of soap production.[3] It mentions the key ingredient, alkali, which later becomes crucial to modern chemistry, derived from al-qaly or "ashes".

By the thirteenth century, the manufacture of soap in the Islamic world had become virtually industrialized, with sources in Nablus, Fes, Damascus, and Aleppo.[4]

Medieval Europe

Soapmakers in Naples were members of a guild in the late sixth century (then under the control of the Eastern Roman Empire),[5] and in the eighth century, soap-making was well known in Italy and Spain.[6] The lands of Medieval Spain were a leading soapmaker by 800, and soapmaking began in the Kingdom of England about 1200.[7]

Castile soap, made from olive oil, was produced in Europe as early as the sixteenth century.

Modern History

In modern times, the use of soap has become universal in industrialized nations due to a better understanding of the role of hygiene in reducing the population size of pathogenic microorganisms. Manufactured bar soaps first became available in the late nineteenth century, and advertising campaigns in Europe and the United States helped to increase popular awareness of the relationship between cleanliness and health. By the 1950s, soap had gained public acceptance as an instrument of personal hygiene.

A bar of blue-white offenbach soap.

Commercial soap production

Until the Industrial Revolution, soap-making was done on a small scale and the product was rough. In 1789, Andrew Pears started making a high-quality, transparent soap in London. He and his grandson, Francis Pears, opened a factory in Isleworth in 1862. William Gossage produced low-priced, good quality soap from the 1850s. Robert Spear Hudson began manufacturing a soap powder in 1837, initially by grinding the soap with a mortar and pestle. William Hesketh Lever and his brother James bought a small soap works in Warrington in 1885 and founded what became one of the largest soap businesses, now called Unilever. These soap businesses were among the first to employ large-scale advertising campaigns to sell the output of their factories.

Forms of soap

Soap usually comes in a solid, molded form, called a bar, based on its typical shape. The use of thick liquid soap has also become widespread, especially from soap dispensers in public washrooms. When applied to a soiled surface, soapy water effectively holds particles in suspension, which can then be rinsed off with clean water.

Components of detergents and their functions

As noted above, soaps are salts of fatty acids. A molecule of soap may be represented as follows:

(fatty end) :CH3-(CH2)n - COO−Na+: (water soluble end)

Thus, each molecule of soap has (a) an ionic end, which is hydrophilic (water-attracting) and soluble in water; and (b) a nonpolar hydrocarbon chain that is hydrophobic (water-repelling) that can attach to nonpolar materials such as grease and oil. These molecules form bridges between water and oil, breaking up the oil and forming an emulsion consisting of oil droplets suspended in water. Substances made up of such molecules are called surfactants. They reduce the surface tension of water, and they reduce interfacial tension between oil and water by adsorbing at the liquid-liquid interface.

Diagram of how soap works.

Surfactants are key components of detergents in general. Because of their presence in detergents, oil and associated dirt particles become solubilized and can be rinsed away with clean water.

Many types of organic compounds can function as surfactants. They (and the detergents that contain them) are often classified into four groups: anionic, cationic, zwitterionic (with plus and minus charges), and non-ionic. In the case of non-ionic surfactants, the hydrophilic nature of one end is conferred by the presence of special functional groups such as hydroxyl groups. Most brands of laundry detergent have anionic or nonionic surfactants or a mixture of the two, although cationic surfactants have also been used. The use of cationic and anionic surfactants together is incompatible in the same detergent. The usual content of surfactants in a typical detergent is about 8-18 percent.

In addition to surfactants, detergents various other components that serve different functions. A given detergent may contain several of the following components:

  • Abrasives that scour the surfaces.
  • Substances that modify or control pH, or affect the performance or stability of other ingredients. For example, acids may be used for descaling, or caustics to destroy dirt.
  • Water softeners counteract the effect of "hardness" ions (particularly calcium and magnesium ions). Some form of sodium phosphate (such as trisodium orthophosphate, monosodium orthophosphate, or a tripolyphosphate) can be used here. In some locations, phosphate is no longer used due to environmental concerns, as phosphates in surface waters stimulate algal bloom. As alternatives, other chelating agents or ion exchange materials are used.
  • Oxidizing agents (oxidizers) that bleach surfaces and destroy dirt. In North America, sodium hypochlorite based bleach additives are more common. These work at lower temperatures and do not need activation. In Europe, peroxide-based bleaches are prevalent.
  • Fillers, forming a bulk component in many laundry detergents, modify the physical properties of the material. In solid detergents, sodium sulfate or borax can be used to make the powder free-flowing. In liquid detergents, alcohols are added to increase the solubility of the compounds and to lower the mixture's freezing point.
  • Non-surfactant materials that keep dirt in suspension.
  • Enzymes that digest proteins, fats, or carbohydrates. They help remove biological stains (such as stains from grass or blood). Enzymes produced by the bacteria Bacillus subtilis and Bacillus licheniformis are often used.
  • Ingredients that modify the foaming properties of the cleaning surfactants, to either stabilize or counteract foam.
  • Additional ingredients include optical brighteners, fabric softeners, colors, and perfumes.

The material to be cleaned dictates the composition of the detergent that should be used and the apparatus to be used. For instance, the following are examples of different glass-cleaning agents that are appropriate for different contexts:

  • A chromic acid solution is used to get glass very clean for precision-demanding purposes, such as analytical chemistry
  • A high-foaming mixture of surfactants with low skin irritation is needed for hand washing of drinking glasses in a sink or dishpan.
  • Any of various non-foaming compositions are used for glasses in a dishwashing machine.
  • An ammonia-containing solution is useful for cleaning windows, with no need for rinsing.
  • Windshield washer fluid is useful especially when a vehicle is in motion.

Soap making

Handmade soaps sold at a shop in Hyères, France.

Some individuals continue to make soap in the home. The traditional name "soaper," for a soap maker, is still used by those who make soap as a hobby. Those who make their own soaps are also known as soap crafters.

The most popular process for handmade soaps today is the cold process, where oils such as olive oil are reacted with lye. Some soap makers use the "melt and pour" process, where a pre-made soap base is melted and poured into individual molds. Some soapers also practice other processes, such as the historical hot process, and make special soaps such as clear soap (glycerin soap).

Use of fats and oils

Handicraft made Marseille soap.

Soap is derived from either oils or fats. Sodium tallowate, a common ingredient in many soaps, is derived from rendered beef fat. Soap can also be made of vegetable oils, such as palm oil, and the product is typically softer.

An array of quality oils and butters are used in the process, such as olive, coconut, palm, cocoa butter, hemp oil and shea butter. Each oil chosen by the soap maker has unique characteristics that provide different qualities to handmade soaps including mildness, lathering and hardness. For example, olive oil provides mildness in soap; coconut oil provides lots of lather while coconut and palm oils provides hardness. Most common, though, is a combination of coconut, palm, and olive oils.

If soap is made from pure olive oil it may be called Castile soap or Marseille soap. The term "Castile soap" is also sometimes applied to soaps with a mix of oils, but a high percentage of olive oil.

Reactions with alkali

When fat (or oil) is reacted with lye (sodium hydroxide), the product is a hard soap. When fat is reacted with potassium hydroxide, the product is a soap that is either soft or liquid. Either reaction is known as saponification. The fat is hydrolyzed by the alkali, yielding glycerol and crude soap. Historically, the alkali used was potassium hydroxide, made from the deliberate burning of vegetation such as bracken, or from wood ashes.

Cold and hot processes

Hot process

In the hot-process method, lye and fat are boiled together at 80–100°C until saponification occurs. After saponification, the soap is sometimes precipitated from the solution by adding salt, and the excess liquid drained off. The hot, soft soap is then spooned into a mold.

The hot-process method was used when the purity of lye was unreliable, and when naturally produced lye, such as potash, was used. The main benefit of hot processing is that the exact concentration of the lye solution does not need to be known to perform the process with adequate success.

Unlike cold-processed soap, hot-processed soap can be used right away because lye and fat saponify more quickly at the higher temperatures used in hot-process soap making.

Cold process

In the cold-process method, fats such as olive oil are reacted with lye, at a temperature that is sufficiently above room temperature to ensure the liquefaction of the fat being used. It requires that the lye and fat be kept warm after mixing to ensure that the soap is completely saponified.

The cold process requires exact measurement of lye to fat using saponification charts, to ensure that the finished product is mild and skin friendly. Excess unreacted lye in the soap will result in a very high pH and can burn or irritate skin. Not enough lye, and the soap is greasy and oily. Most soap makers formulate their recipes with a 4-10 percent discount of lye so that all of the lye is reacted and that excess fat is left for skin conditioning benefits. (Saponification charts can also be used in hot-process soap making, but are not as necessary as for the cold-process method.)

The lye is dissolved in water. Then oils are heated, or melted if they are solid at room temperature. Once both substances have cooled to approximately 100-110°F, and are no more than 10 degrees Fahrenheit apart in temperature, they may be combined. This lye-fat mixture is stirred until it reaches a stage called "trace"—the point at which the saponification process is sufficiently advanced that the soap has begun to thicken. (Modern-day amateur soap makers often use a stick blender to speed this process.). There are varying levels of trace: light, medium, and heavy.

Essential oils, fragrance oils, botanicals, herbs, oatmeal or other additives are added at light trace, just as the mixture starts to thicken. The batch is then poured into molds, kept warm with towels or blankets, and left to continue saponification for 18 to 48 hours.

After the insulation period, the soap is firm enough to be removed from the mold and cut into bars. At this time, it is safe to use the soap since saponification is complete. However, cold-process soaps are typically cured and hardened on a drying rack for 2-6 weeks (depending on initial water content) before use.

Purification and finishing

The common process of purifying soap involves removal of sodium chloride, sodium hydroxide, and glycerol. These components are removed by boiling the crude soap curds in water and re-precipitating the soap with salt.

Most of the water is then removed from the soap. This was traditionally done on a chill roll which produced the soap flakes commonly used in the 1940s and 1950s. This process was superseded by spray dryers and then by vacuum dryers.

The dry soap (approximately 6-12 percent moisture) is then compacted into small pellets. These pellets are now ready for soap finishing, the process of converting raw soap pellets into a salable product, usually bars.

Soap pellets are combined with fragrances and other materials and blended to homogeneity in an amalgamator (mixer). The mass is then discharged from the mixer into a refiner which, by means of an auger, forces the soap through a fine wire screen. From the refiner the soap passes over a roller mill (French milling or hard milling) in a manner similar to calendering paper or plastic or to making chocolate liquor. The soap is then passed through one or more additional refiners to further plasticize the soap mass. Immediately before extrusion it passes through a vacuum chamber to remove any entrapped air. It is then extruded into a long log or blank, cut to convenient lengths, passed through a metal detector and then stamped into shape in refrigerated tools. The pressed bars are packaged in many ways.

Sand or pumice may be added to produce a scouring soap. This process is most common in creating soaps used for human hygiene. The scouring agents serve to remove dead skin cells from the surface being cleaned. This process is called exfoliation. Many newer materials are used for exfoliating soaps which are effective but do not have the sharp edges and poor size distribution of pumice.

Uses

Detergents are mainly used in products for personal hygiene, dishwashing, and laundry. In addition, detergents are often added to a variety of products, to prevent the buildup of undesirable deposits. Some products that may contain detergents include:

  • toothpastes
  • antiseptic agents
  • dry-cleaning solutions
  • gasoline
  • lubricating oils

A nature-friendly way of interrupting an ant trail is to pour soapy water on the trail. The soapy water destroys the scent the ants were following to get to food.

Disadvantages

Today, fat-based soaps have mostly been superseded by modern detergents. Washing agents do not contain soap for cleaning fabric, but for reducing foam.

The disadvantages of commercial soaps are:

  • Due to the fact that most commercial soaps eliminate the glycerine from soaps to use in other industries, this deprives the skin of the natural, moisturising glycerine and generally leaves the skin feeling dry.
  • Some antibacterial soaps have chemicals killing bacteria that coexist on the skin's surface and are essential to skin health.
  • Soap-based products often contain the additive sodium laureth sulfate, which research has found to be harsh on skin. This product is also present in many non-soap cleaners for personal hygiene (such as shampoos, bathfoams, toothpaste).
  • Soap can react mildly basically with fabrics resulting in damage over the long term. This is usually due to excess sodium hydroxide (NaOH, an alkali/base) left from manufacture, but can also be caused by the very slight presence of NaOH from the equilibrium reaction:
    R-COO-Na + H2O ↔ R-COO- + Na+ + H2O ↔ R-COOH + NaOH
    However, this equilibrium strongly favors the left-hand side so the fraction of NaOH formed is minuscule
  • Soap reacts with lime to form an insoluble deposit (soap scum) in "hard water":
    2Na+(R-COO)-(aq) + Ca2+(HCO3-)2(aq) → 2Na+(HCO3)-(aq) + Ca(R-COO)2(s) - where R stands for an alkyl group (precipitate)
  • Poorly finished soaps contain alkali (NaOH) and react mildly basically with skin and fabric; commercial products are finished to neutrality or to a weak acid content to prevent this and be more compatible with the skin's slightly acidic pH.
  • Commercial products use chelating molecules (sequestrants), often EDTA derivatives to bind with any free Ca or Mg ions and prevent soap scum. These also help reduce fragrance loss, discoloration. and rancidity.
  • Castile soap has a very high alkalinity level, measured at about 9. pH of skin and hair has a slightly acidic pH level known to be about 5 to 6. Due to the high pH level, liquid castile soap is usually not recommended by soapmakers who market this high pH soap for washing hair because it is not pH-balanced and it may cause hair to become dry.

Environmental concerns

In the 1960s, detergent manufacturers waged an advertising battle over who had the longest lasting suds, and detergent compounds quickly appeared in the waterways. Suds began to appear in streams, rivers, and lakes. At the foot of the Niagara Falls, piles of discolored detergent foam rose eight feet high.

Detergents also contain phosphate additives to soften the water and thereby improve the effectiveness of the detergent molecules. It was noted that between 1940 and 1970 the amount of phosphates in city wastewater increased from 20,000 to 150,000 tons per year.

With the increase in phosphates, algal blooms grew splendidly on the excess phosphorus and consumed the majority of all oxygen in the waters, killing fish and plants.

Allowing a detergent to sit on any surface (such as skin or clothes) over time can cause an imbalance in pH and moisture content on the surface, damaging the fabric and injuring the skin.

See also

Notes

  1. ↑ Pliny the Elder, Natural History, XXVIII.191. Retrieved November 14, 2007.
  2. ↑ Soaps and Detergents. Algebra Lab. Retrieved November 17, 2007.
  3. ↑ Jim Al-Khalili, Science and Islam Part 2, BBC Productions.
  4. ↑ Michael Phillips, Nablus' olive oil soap: a Palestinian tradition lives on Institute for Middle East Understanding (IMEU), March 11, 2008. Retrieved October 14, 2015.
  5. ↑ Harald Kleinschmidt, Understanding the Middle Ages: The Transformation of Ideas and Attitudes in the Medieval world (Boydell & Brewer, 2000, ISBN 085115770X).
  6. ↑ Raymond G. Bistline, Jr., "Anionic and Related Lime Soap Dispersants," in Anionic surfactants: organic chemistry, Helmut Stache, (ed.) (CRC Press, 1996, ISBN 0824793943).
  7. ↑ History of Soap Flakes. Retrieved October 14, 2015.

References
ISBN links support NWE through referral fees

  • Broze, Guy, (ed.). Handbook of Detergents, Part A: Properties. Surfactant Science Series. New York: M. Dekker, 1999. ISBN 0824714172.
  • Garzena, Patrizia, and Marina Tadiello. Soap Naturally: Ingredients, Methods and Recipes for Natural Handmade Soap. Mayfield, N.S.W.: Programmer, 2004. ISBN 0975676407.
  • Kleinschmidt, Harald. Understanding the Middle Ages: The Transformation of Ideas and Attitudes in the Medieval world. Boydell & Brewer, 2000. ISBN 085115770X.
  • Lange, K. Robert. Surfactants: A Practical Handbook. Munich: Hanser Publishers, 1999. ISBN 1569902704.
  • Maine, Sandy. The Soap Book: Simple Herbal Recipes. Loveland: Interweave Press, 1995. ISBN 1883010144.
  • Stache, Helmut (ed.). Anionic surfactants: organic chemistry. CRC Press, 1996. ISBN 0824793943.
  • Urban, David G. How to Formulate & Compound Industrial Detergents. BookSurge Publishing, 2003. ISBN 1588988686.

External links

All links retrieved January 30, 2023.

Credits

New World Encyclopedia writers and editors rewrote and completed the Wikipedia article in accordance with New World Encyclopedia standards. This article abides by terms of the Creative Commons CC-by-sa 3.0 License (CC-by-sa), which may be used and disseminated with proper attribution. Credit is due under the terms of this license that can reference both the New World Encyclopedia contributors and the selfless volunteer contributors of the Wikimedia Foundation. To cite this article click here for a list of acceptable citing formats.The history of earlier contributions by wikipedians is accessible to researchers here:

The history of this article since it was imported to New World Encyclopedia:

Note: Some restrictions may apply to use of individual images which are separately licensed.

Retrieved from https://www.newworldencyclopedia.org/p/index.php?title=Soaps_and_Detergents&oldid=1098614

Content is available under Creative Commons Attribution/Share-Alike License; additional terms may apply. See Terms of Use for details.
Copyright Logo
Powered by MediaWiki