Difference between revisions of "Paint" - New World Encyclopedia

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[[Image:GreenPaintBucketRome.jpg|thumb|right|200px|''Dried green paint'']]
 
[[Image:GreenPaintBucketRome.jpg|thumb|right|200px|''Dried green paint'']]
 
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'''Paint''' is the general term for a family of products used to protect and add [[color]] to an object or surface by covering it with a pigmented coating. Paint can be applied to almost any kind of object. It is used for aesthetic purposes, such as in producing works of art or manuscript illumination, and for practical purposes, such as in coating and protecting buildings, vehicles, and industrial machinery. Paint is also used to make signs for advertising and directing traffic. It should be noted that some paints and the materials used to make them are toxic and may cause sickness and death. Even nontoxic paints, if not disposed of properly, can pollute the land or water. Therefore, care needs to be exerted when using and disposing of paints.
'''Paint''' is the general term for a family of products used to protect and add [[color]] to an object or surface by covering it with a pigmented coating. As a verb, [[painting]] is the application of paint. One who paints is called a [[painter]].
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{{toc}}
 
 
Paint can be applied to almost any kind of object. It is used, among many other uses, in the production of [[art]], in [[industrial coating]], a driving aid ([[lane markings]]), a [[preservative]] (to prevent [[corrosion]] or water damage).
 
 
 
 
==Components==
 
==Components==
 +
[[Image:Artists paints.jpg|thumb|right|250px|Both professional and amateur artists can take advantage of the wide variety of artists' paints available.]]
 +
A paint generally has three types of components: a [[Binder (material)|binder]], a [[diluent]], and additives. Of these, only the binder is absolutely required. It is the part that eventually solidifies to form the dried paint film. Typical binders include synthetic or natural [[resin]]s, such as [[Acryl group|acrylic]]s, [[polyurethane]]s, [[polyester]]s, [[melamine]]s, [[Oil paint|oil]]s, and [[latex]].
  
There are generally three components to a paint: [[Binder (material)|binder]], [[diluent]] and additives. However, only the binder is absolutely required. The binder is the part which eventually solidifies to form the dried paint film. The diluent serves to adjust the viscosity of the paint. It is volatile and does not become part of the paint film. Anything else is an additive.  
+
The diluent serves to adjust the viscosity of the paint. It is volatile and does not become part of the paint film. Typical diluents include organic solvents such as [[alcohol]]s, [[ketone]]s, and [[ester]]s. Water is also a common diluent. Sometimes volatile synthetic resins also serve as diluents.
  
Typical binders include synthetic or natural [[resin]]s such as [[Acryl group|acrylic]]s, [[polyurethane]]s, [[polyester]]s, [[melamine]]s, [[Oil paint|oil]]s, or [[latex]].
+
Components other than the binder and diluent are called additives. Typical additives include pigments, [[dye]]s, [[catalyst]]s, thickeners, stabilizers, emulsifiers, texturizers, adhesion promoters, and flatteners (de-glossing agents).
  
Typical diluents include organic solvents such as [[alcohol]]s, [[ketone]]s, [[ester]]s, [[glycol]] ethers, and the like. Water is a common diluent. Sometimes volatile low-molecular weight synthetic resins also serve as diluents.
+
After application, the paint solidifies and becomes tack-free. Depending on the type of binder, this hardening may be a result of curing (polymer formation), [[evaporation]], or cooling. The curing process usually involves cross-linking of the molecules of the binder, usually in the presence of a catalyst. Cured-film paints can be either solvent-borne or waterborne.
  
Typical additives include [[pigment]]s, [[dye]]s, [[catalyst]]s, thickeners, stabilizers, [[emulsifier]]s, texturizers, adhesion promoters, flatteners (de-glossing agents), and the like.
+
Some waterborne paints are [[emulsion]]s of solid binders in water, and they are often referred to simply as "emulsions". When the diluent evaporates, the molecules of the binder coalesce and form polymers, leaving a solid film. Such emulsion paints are also known as latex paints. The polymer itself is not soluble in water, and as a result the paint is water resistant after it has dried.
  
After application, the paint solidifies and becomes tack-free. Depending on the type of binder, this hardening may be a result of curing ([[polymerization]]), [[evaporation]], or even cooling. In oil-based paint, curing takes the form of [[oxidation]], for example oxidation of [[linseed oil]] to form linoxin to create a [[varnish]]. Other common cured films are prepared from [[Cross-link|crosslinkers]], such as polyurethane or melamine resins, reacted with acrylic polyester or polyurethane resins, often in the presence of a catalyst which serves to make the curing reaction proceed more quickly or under milder conditions. These cured-film paints can be either solvent-borne or waterborne.
+
Some paint films are formed by cooling of the binder. For example, [[wax]] paints are liquid when warm and harden upon cooling.
 
 
Other waterborne paints are [[emulsion]]s of solid binders in water (in fact, such paints are often called simply "emulsions"). When the diluent evaporates, the molecules of the binder coalesce to form a solid film. Such emulsion paints are also known as latex paints because the [[polymer]] is formed through an [[emulsion polymerization]] through which the monomers are emulsified in a water-continuous phase. The polymer itself is not [[soluble]] in water and hence the paint is water resistant after it has dried. Residual [[surfactant]]s in the paint as well as [[hydrolyze|hydrolytic]] effects with some polymers cause the paint to remain susceptible to softening and, over time, degradation by water.
 
 
 
Still other films are formed by cooling of the binder. For example, [[encaustic]] or [[wax]] paints are liquid when warm, and harden upon cooling.
 
  
 
==Art==
 
==Art==
 
:''Main article: [[Painting]]''
 
:''Main article: [[Painting]]''
[[Image:Artists paints.jpg|thumb|right|250px|There is a wide variety of artists' paints available for the professional or amateur artist.]]
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[[Image:God2-Sistine Chapel.png|thumb|right|Michelangelo's depiction of the creation of Adam.]]
Since the time of the [[Renaissance]], [[siccative]] (drying) oil paints, primarily linseed oil, have been the most commonly used kind of paints in fine art applications; oil paint is still common today. However, in the [[20th century]], water-based paints, including [[watercolor]]s and [[acrylic paint]]s, became very popular with the development of [[latex]] and [[Acryl group|acrylic]] pigment suspensions. Milk paints (also called [[casein]]), where the medium is derived from [[milk]], were popular in the [[19th century]] and are still available today. [[Egg tempera]] (where the medium is an [[emulsion]] of [[egg yolk]] mixed with oil) is still in use as well, as are encaustic [[wax]]-based paints. [[Gouache]] is a variety of watercolor paint which was also used in the [[Middle Ages]] and Renaissance for manuscript illumination. The pigment was often made from ground semiprecious stones such as [[lapis lazuli]] and the binder made from either [[gum arabic]] or [[egg white]]. Gouache is commercially available today.
 
  
[[Poster paint]] has been used primarily in the creation of student works, or by children.
+
Since the time of the [[Renaissance]], siccative (drying) oil paints (containing primarily linseed oil) have been the most commonly used type of paints in the fine arts. In the twentieth century, however, water-based paints—including [[watercolor]]s and [[acrylic paint]]s—became very popular, based on the development of [[latex]] and [[Acryl group|acrylic]] pigment suspensions. Milk paints (also called ''casein''), in which the medium is derived from [[milk]], were popular in the nineteenth century and are still available today. [[Egg tempera]], in which the medium is an emulsion of [[egg yolk]] mixed in oil, is still in use as well, as are [[wax]]-based paints. [[Gouache]] is a form of watercolor paint that was also used in the [[Middle Ages]] and Renaissance for manuscript illumination. The pigment was often made from ground semiprecious stones, such as [[lapis lazuli]], and the binder was made from either gum arabic or egg white. Gouache is commercially available today. [[Poster paint]] is usually used for artwork by children.
  
==Pigment==
+
==Pigments and dyes==
:''Main article: [[Pigment]]''
+
A distinction is usually made between a '''pigment''' and a '''dye'''. A pigment is a colored substance (or colorant) that is not soluble in the vehicle (medium or matrix) to which it is added, while a dye is a colored substance that is either a liquid or is soluble in the medium used. In addition, a dye has an affinity for the substrate to which it is applied, while a pigment has no affinity for the substrate. Pigments and dyes can be organic or inorganic, obtained from natural products or prepared by chemical synthesis.
Pigments, usually insoluble powders, are used both to provide color, and to make paint opaque, thus protecting the substrate from the harmful effects of ultraviolet light while also increasing a paint's hiding power.  
 
  
Some pigments are toxic, such as those used in [[lead paint]]. Paint manufacturers replaced lead white with a less toxic substitute, which can even be used to color food '''titanium white''' (Titanium Dioxide) which was first used in paints in the [[19th century]]. The titanium white used in most paints today is often coated with silicon or aluminum oxides for better durability.  
+
At times, a given colorant can be called a pigment or a dye, depending on the vehicle in which it is used. In some cases, a pigment is made by precipitating a soluble dye with a metallic salt. The resulting pigment is called a "lake."
  
Some newer paints - called prism paint - can produce effects where the color changes depending on the angle (orientation) at which it is viewed.  Modern [[United States|U.S.]] and [[Canada|Canadian]] banknotes, specifically the newer higher denomination notes, have this effect on them. This effect is produced by having pigment molecules that are long and thin and are meant to dry in a specific orientation, with different ends of the molecule being different colors.
+
Pigments are used in the coloring of paint, [[ink]], [[plastic]], [[Cloth|fabric]], and other materials. When added to paint, a pigment not only provides color but also makes the paint opaque, thus protecting the painted object from the harmful effects of ultraviolet light while also hiding defects on the object's surface.
  
==Application==
+
When visible [[light]] shines on a pigment, the pigment selectively absorbs some colors (wavelengths) of the light whilst reflecting others. The color of the pigment is the combination of colors (wavelengths) that are reflected.
Paint can be applied as a solid, a gaseous suspension or a liquid. Techniques vary depending on the practical or artistic results desired.
 
  
As a solid (usually in industrial and automotive applications), the paint is applied as a very fine powder, then baked at high temperature. This melts the powder and causes it to adhere (stick) to the surface. The reasons for doing this involve the chemistries of the paint, the surface itself, and perhaps even the chemistry of the substrate (the overall object being painted).
+
Some pigments are toxic, such as those used in [[lead paint]]. For this reason, paint manufacturers have replaced lead white with a less toxic substitute called ''titanium white'' (composed mainly of titanium dioxide). This substitute, first used in paints in the nineteenth century, can even be used to color food. The titanium white used in most paints today is often coated with silicon or aluminum oxides for better durability.
  
As a gas or as a gaseous suspension, the paint is suspended in solid or liquid form in a gas that is sprayed on an object.  The paint sticks to the object.  The reasons for doing this include:
+
Some newer paints, called prism paints, can produce effects where the color appears to change, depending on the angle (orientation) from which it is viewed. These effects can be seen in modern [[United States|U.S.]] and [[Canada|Canadian]] banknotes, specifically the newer, higher denomination notes.
*the application mechanism is air and thus no solid object ever touches the object being painted;
+
 
*the distribution of the paint is very uniform so there are no sharp lines
+
==Application methods==
*it is possible to deliver very small amounts of paint or to paint very slowly;
+
Paint can be applied as a solid, liquid, or gaseous suspension. Application techniques vary, depending on the practical or artistic results desired.
*a chemical (typically a [[solvent]]) can sprayed along with the paint to dissolve together both the delivered paint and the chemicals on the surface of the object being painted;
 
*some chemical reactions in paint involve the orientation of the paint [[molecules]].
 
  
In the liquid application, paint can be applied by direct application using [[Brush|brushes]], [[paint rollers]], [[Palette knife|blades]], other instruments, or body parts.  Examples of body parts include [[fingerpainting]], where the paint is applied by hand, [[whole-body painting]] (popular in the [[1960s]] [[avant-garde]] movement), and [[cave painting]], in which a [[pigment]] (usually finely-ground [[charcoal]]) is held in the mouth and spat at a wall ('''Note:''' some paints are [[toxic]] and might cause [[death]] or permanent injury).
+
The solid form of paint is a fine powder that is applied to the object's surface and baked at high temperature. The heat melts the powder and causes it to stick to the surface. Solid paint is usually used for industrial and automotive applications.
  
Rollers generally have a handle that allows for different lengths of poles which can be attached to allow for painting at different heights. Generally, roller application takes two coats for even color. A roller with a thicker [[nap]] is used to apply paint on uneven surfaces. Edges are often finished with an angled brush.
+
Paint in the liquid form can be applied directly using brushes, [[paint rollers]], blades, and other instruments. Liquid paint may also be applied using one's fingers, as is popular for artwork by children, or by dipping the object in paint. Roller application generally takes two coats for even color. Edges are often finished with an angled brush. After liquid paint is applied, there is an interval called "open time" during which the paint can be blended with additional painted regions (at the "wet edge").
  
After liquid paint is applied, there is an interval during which it can be blended with additional painted regions (at the "wet edge") called "open time." The open time of an emulsion paint can be extended by adding [[white spirit]], similar glycols such as Dowanol™ (propylene glycol ether) or commercial open time prolongers. This can also facilitate the mixing of different wet paint layers for aesthetic effect.
+
A gaseous suspension of paint consists of solid particles or liquid droplets that are suspended in a gas (usually air) and sprayed on an object. There are several advantages to using this process:
 +
*paint can be applied to an object without using instruments (such as brushes or rollers) that would touch the object;
 +
*the paint can be uniformly distributed, without leaving any sharp lines;
 +
*it is possible to deliver very small amounts of paint or to paint very slowly;
 +
*a chemical (typically a solvent) can be sprayed along with the paint, thereby dissolving together both the delivered paint and the chemicals on the surface of the object being painted.
  
Paint may also be applied by flipping or spraying the paint, [[dripping]], or by dipping an object in paint.
+
Care needs to be taken when applying paints, especially if they are toxic.
  
 
==Product Variants==
 
==Product Variants==
*[[Wood stain]] is a type of paint that is very "thin," that is, low in viscosity, and formulated so that the pigment penetrates the surface rather than remaining in a film on top of the surface. Stain is predominantly [[pigment]] or [[dye]] and solvent with little binder, designed primarily to add color without providing a surface coating.  
+
*Wood stain is a type of paint that is very "thin" (low in viscosity) and formulated so that the pigment penetrates the surface rather than remaining as a film on the surface. Stain is predominantly pigment or dye and solvent with little binder, designed primarily to add color without providing a surface coating.
*[[Varnish]] and [[shellac]] provide a protective coating without changing the color. They are paints without pigment.  
+
*[[Varnish]] and [[shellac]] provide a protective coating without changing the color. They are paints without pigment.
*[[Lacquer]] is usually a fast-drying solvent-based paint or varnish that produces an especially hard, durable finish.
+
*[[Lacquer]] is usually a fast-drying, solvent-based paint or varnish that produces an especially hard, durable finish.
 
*An [[enamel paint]] is a paint that dries to an especially hard, usually glossy, finish. Enamel can be made by adding varnish to oil-based paint.
 
*An [[enamel paint]] is a paint that dries to an especially hard, usually glossy, finish. Enamel can be made by adding varnish to oil-based paint.
 
*[[Fingerpaint]]
 
*[[Fingerpaint]]
*[[Inks]] are similar to paints, except they are typically made using dyes exclusively (no pigments), and are designed so as not to leave a thick film of binder.
+
*[[Inks]] are similar to paints, except that they are typically made using dyes (not pigments) and are designed so as not to leave a thick film of binder.
*[[Titanium dioxide]] is extensively used for both house paint and artist's paint, because it is permanent and has good covering power. Titanium oxide pigment accounts for the largest use of the element. Titanium paint is an excellent reflector of infrared, and is extensively used in solar observatories where heat causes poor seeing conditions.
+
*[[Titanium dioxide]] is extensively used for both house paint and artist's paint, because it is permanent and has good covering power. Titanium paint is an excellent reflector of infrared light. It is therefore used extensively in solar observatories, where heat causes poor seeing conditions.
*[[Anti-climb paint]] is a non-drying paint that appears normal whilst being extremely slippery. It is usually used on drainpipes and ledges to deter burglars and vandals from climbing them, and is found in many public places. When a person attempts to climb objects coated with the paint, it rubs off onto the climber, as well as making it hard for them to climb.
+
*[[Anti-climb paint]] is a non-drying paint that appears normal while being extremely slippery. It is usually used on drainpipes and ledges to deter burglars and vandals from climbing them, and is found in many public places. When a person attempts to climb an object coated with the paint, some of the paint rubs off onto the climber, who also finds it hard to climb.
 +
 
 +
==Some historical examples==
 +
 
 +
Painted walls have been discovered at certain sites of ancient civilizations. For instance, ancient walls at Dendera, [[Egypt]], were painted perhaps 2,000 years ago and have remained exposed to the air, but they still possess perfect brilliancy of color. The Egyptians mixed their colors with some gummy substance and applied the colors detached from one another without any blending. It appears that they used six colors: white, black, blue, red, yellow, and green.
  
==History==
+
[[Pliny the Elder|Pliny]] mentions that in the town of Ardea, he observed ceilings that had been painted prior to the foundation of [[Rome]]. He expresses great surprise and admiration at their freshness, after the lapse of many centuries.
  
Ancient painted walls, to be seen at [[Dendera]], [[Egypt]], although exposed for many ages to the open air, still possess a perfect brilliancy of color, as vivid as when painted, perhaps 2000 years ago. The Egyptians mixed their colors with some gummy substance, and applied them detached from each other without any blending or mixture. They appeared to have used six colors: white, black, blue, red, yellow, and green.  They first covered the field entirely with white, upon which they traced the design in black, leaving out the lights of the ground color. They used minium for red, and generally of a dark tinge.
+
== Biological and organic pigments ==
 +
*[[Heme]]/porphyrin-based: [[chlorophyll]], bilirubin, hemocyanin, [[hemoglobin]], myoglobin
 +
*Light-emitting: [[luciferin]]
 +
* Lipochromes:
 +
**[[Carotenoid]]s: alpha and beta [[carotene]], anthocyanin, lycopene, rhodopsin
 +
**[[Xanthophyll]]s: canthaxanthin, zeaxanthin, lutein
 +
* Photosynthetic: [[chlorophyll]], phycobilin
 +
* [[organic compound|Organic]]: Pigment Red 170, phthalocyanine, Phthalo Green, Phthalo Blue, Alizarin, Alizarin Crimson, [[crimson]], Indian yellow, [[indigo]], quinacridone, quinacridone magenta, woad.
 +
* Resin: gamboge
 +
* Polyene enolates: a class of red pigments unique to [[parrot]]s
  
[[Pliny the Elder|Pliny]] mentions some painted ceilings in his day in the town of [[Ardea]], which had been executed at a date prior to the foundation of [[Rome]]. He expresses great surprise and admiration at their freshness, after the lapse of so many centuries.
+
* Other: hematochrome, [[melanin]], Phthalocyanine blue, urochrome, Van Dyke brown
  
:''See also'' [[lacquer]], [[varnish]], [[fresco]]
+
==Inorganic pigments==
 +
*[[Carbon]] pigments: bone black (also known as bone char), carbon black, ivory black, vine black, lampblack, Mars black
 +
*[[Cadmium]] pigments: cadmium pigments, Cadmium Green, Cadmium Red, Cadmium Yellow, Cadmium Orange
 +
*[[Iron]] pigments: Caput Mortuum, Prussian blue, oxide red, red ochre, Sanguine, Venetian red
 +
*[[Chromium]] pigments: Chrome Green, chrome yellow
 +
*[[Cobalt]] pigments: cobalt blue, cerulean blue
 +
*[[Lead]] pigments: lead white, Naples yellow, Cremnitz White, Foundation White, red lead
 +
*[[Copper]] pigments: Paris Green, verdigris
 +
*[[Titanium]] pigments: titanium dioxide, titanium white
 +
*[[Sulfur]] pigments: ultramarine, Ultramarine Green Shade, French Ultramarine, vermilion
 +
*Chrome pigments: viridian
 +
*[[Zinc]] pigments: zinc white
 +
*Clay earth pigments: sienna, raw sienna, burnt sienna, umber, raw umber, burnt umber, yellow ochre
 +
 
 +
==See also==
 +
*[[Dye]]
 +
*[[Fresco]]
 +
* [[Pigment]]
 +
*[[Varnish]]
  
 
==External links==
 
==External links==
*[http://www.realpaints.com/history.htm History of Paint]
+
All links retrieved November 18, 2022.
 +
 
 
*[http://www.ibiblio.org/ecolandtech/rural-skills/homemade/homemade-paint 20 recipes for homemade paint] (text)
 
*[http://www.ibiblio.org/ecolandtech/rural-skills/homemade/homemade-paint 20 recipes for homemade paint] (text)
*[http://www.ravenna.portage.k12.oh.us/schools/childcare/hpaint.htm Homemade Paint Recipes for Children]
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* [http://webexhibits.org/pigments/ Pigments through the ages]
* [http://www.passionforpaint.com/OilPaints.html The Quest of Purchasing Oil Paints]
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* [http://news.bbc.co.uk/1/hi/sci/tech/733747.stm Earliest evidence of art found]
* [http://graypainting.com/paint_faq.htm Comparing Commercial Paints FAQ]
 
*For a glossary of terms used in the paint industry go to [http://www.occa.org.za Oil & Colour Chemists' Association] and click on Paintopedia.
 
 
 
  
 
[[Category:Physical sciences]]
 
[[Category:Physical sciences]]
 
[[Category:Chemistry]]
 
[[Category:Chemistry]]
[[Category:Painting materials]]
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{{credit2|Paint|47844807|Pigment|46926536}}
[[Category:Matter]]
 
[[Category:Soft matter]]
 
 
 
{{credit|47844807}}
 

Latest revision as of 06:16, 18 November 2022


Dried green paint

Paint is the general term for a family of products used to protect and add color to an object or surface by covering it with a pigmented coating. Paint can be applied to almost any kind of object. It is used for aesthetic purposes, such as in producing works of art or manuscript illumination, and for practical purposes, such as in coating and protecting buildings, vehicles, and industrial machinery. Paint is also used to make signs for advertising and directing traffic. It should be noted that some paints and the materials used to make them are toxic and may cause sickness and death. Even nontoxic paints, if not disposed of properly, can pollute the land or water. Therefore, care needs to be exerted when using and disposing of paints.

Components

Both professional and amateur artists can take advantage of the wide variety of artists' paints available.

A paint generally has three types of components: a binder, a diluent, and additives. Of these, only the binder is absolutely required. It is the part that eventually solidifies to form the dried paint film. Typical binders include synthetic or natural resins, such as acrylics, polyurethanes, polyesters, melamines, oils, and latex.

The diluent serves to adjust the viscosity of the paint. It is volatile and does not become part of the paint film. Typical diluents include organic solvents such as alcohols, ketones, and esters. Water is also a common diluent. Sometimes volatile synthetic resins also serve as diluents.

Components other than the binder and diluent are called additives. Typical additives include pigments, dyes, catalysts, thickeners, stabilizers, emulsifiers, texturizers, adhesion promoters, and flatteners (de-glossing agents).

After application, the paint solidifies and becomes tack-free. Depending on the type of binder, this hardening may be a result of curing (polymer formation), evaporation, or cooling. The curing process usually involves cross-linking of the molecules of the binder, usually in the presence of a catalyst. Cured-film paints can be either solvent-borne or waterborne.

Some waterborne paints are emulsions of solid binders in water, and they are often referred to simply as "emulsions". When the diluent evaporates, the molecules of the binder coalesce and form polymers, leaving a solid film. Such emulsion paints are also known as latex paints. The polymer itself is not soluble in water, and as a result the paint is water resistant after it has dried.

Some paint films are formed by cooling of the binder. For example, wax paints are liquid when warm and harden upon cooling.

Art

Main article: Painting
Michelangelo's depiction of the creation of Adam.

Since the time of the Renaissance, siccative (drying) oil paints (containing primarily linseed oil) have been the most commonly used type of paints in the fine arts. In the twentieth century, however, water-based paints—including watercolors and acrylic paints—became very popular, based on the development of latex and acrylic pigment suspensions. Milk paints (also called casein), in which the medium is derived from milk, were popular in the nineteenth century and are still available today. Egg tempera, in which the medium is an emulsion of egg yolk mixed in oil, is still in use as well, as are wax-based paints. Gouache is a form of watercolor paint that was also used in the Middle Ages and Renaissance for manuscript illumination. The pigment was often made from ground semiprecious stones, such as lapis lazuli, and the binder was made from either gum arabic or egg white. Gouache is commercially available today. Poster paint is usually used for artwork by children.

Pigments and dyes

A distinction is usually made between a pigment and a dye. A pigment is a colored substance (or colorant) that is not soluble in the vehicle (medium or matrix) to which it is added, while a dye is a colored substance that is either a liquid or is soluble in the medium used. In addition, a dye has an affinity for the substrate to which it is applied, while a pigment has no affinity for the substrate. Pigments and dyes can be organic or inorganic, obtained from natural products or prepared by chemical synthesis.

At times, a given colorant can be called a pigment or a dye, depending on the vehicle in which it is used. In some cases, a pigment is made by precipitating a soluble dye with a metallic salt. The resulting pigment is called a "lake."

Pigments are used in the coloring of paint, ink, plastic, fabric, and other materials. When added to paint, a pigment not only provides color but also makes the paint opaque, thus protecting the painted object from the harmful effects of ultraviolet light while also hiding defects on the object's surface.

When visible light shines on a pigment, the pigment selectively absorbs some colors (wavelengths) of the light whilst reflecting others. The color of the pigment is the combination of colors (wavelengths) that are reflected.

Some pigments are toxic, such as those used in lead paint. For this reason, paint manufacturers have replaced lead white with a less toxic substitute called titanium white (composed mainly of titanium dioxide). This substitute, first used in paints in the nineteenth century, can even be used to color food. The titanium white used in most paints today is often coated with silicon or aluminum oxides for better durability.

Some newer paints, called prism paints, can produce effects where the color appears to change, depending on the angle (orientation) from which it is viewed. These effects can be seen in modern U.S. and Canadian banknotes, specifically the newer, higher denomination notes.

Application methods

Paint can be applied as a solid, liquid, or gaseous suspension. Application techniques vary, depending on the practical or artistic results desired.

The solid form of paint is a fine powder that is applied to the object's surface and baked at high temperature. The heat melts the powder and causes it to stick to the surface. Solid paint is usually used for industrial and automotive applications.

Paint in the liquid form can be applied directly using brushes, paint rollers, blades, and other instruments. Liquid paint may also be applied using one's fingers, as is popular for artwork by children, or by dipping the object in paint. Roller application generally takes two coats for even color. Edges are often finished with an angled brush. After liquid paint is applied, there is an interval called "open time" during which the paint can be blended with additional painted regions (at the "wet edge").

A gaseous suspension of paint consists of solid particles or liquid droplets that are suspended in a gas (usually air) and sprayed on an object. There are several advantages to using this process:

  • paint can be applied to an object without using instruments (such as brushes or rollers) that would touch the object;
  • the paint can be uniformly distributed, without leaving any sharp lines;
  • it is possible to deliver very small amounts of paint or to paint very slowly;
  • a chemical (typically a solvent) can be sprayed along with the paint, thereby dissolving together both the delivered paint and the chemicals on the surface of the object being painted.

Care needs to be taken when applying paints, especially if they are toxic.

Product Variants

  • Wood stain is a type of paint that is very "thin" (low in viscosity) and formulated so that the pigment penetrates the surface rather than remaining as a film on the surface. Stain is predominantly pigment or dye and solvent with little binder, designed primarily to add color without providing a surface coating.
  • Varnish and shellac provide a protective coating without changing the color. They are paints without pigment.
  • Lacquer is usually a fast-drying, solvent-based paint or varnish that produces an especially hard, durable finish.
  • An enamel paint is a paint that dries to an especially hard, usually glossy, finish. Enamel can be made by adding varnish to oil-based paint.
  • Fingerpaint
  • Inks are similar to paints, except that they are typically made using dyes (not pigments) and are designed so as not to leave a thick film of binder.
  • Titanium dioxide is extensively used for both house paint and artist's paint, because it is permanent and has good covering power. Titanium paint is an excellent reflector of infrared light. It is therefore used extensively in solar observatories, where heat causes poor seeing conditions.
  • Anti-climb paint is a non-drying paint that appears normal while being extremely slippery. It is usually used on drainpipes and ledges to deter burglars and vandals from climbing them, and is found in many public places. When a person attempts to climb an object coated with the paint, some of the paint rubs off onto the climber, who also finds it hard to climb.

Some historical examples

Painted walls have been discovered at certain sites of ancient civilizations. For instance, ancient walls at Dendera, Egypt, were painted perhaps 2,000 years ago and have remained exposed to the air, but they still possess perfect brilliancy of color. The Egyptians mixed their colors with some gummy substance and applied the colors detached from one another without any blending. It appears that they used six colors: white, black, blue, red, yellow, and green.

Pliny mentions that in the town of Ardea, he observed ceilings that had been painted prior to the foundation of Rome. He expresses great surprise and admiration at their freshness, after the lapse of many centuries.

Biological and organic pigments

  • Heme/porphyrin-based: chlorophyll, bilirubin, hemocyanin, hemoglobin, myoglobin
  • Light-emitting: luciferin
  • Lipochromes:
    • Carotenoids: alpha and beta carotene, anthocyanin, lycopene, rhodopsin
    • Xanthophylls: canthaxanthin, zeaxanthin, lutein
  • Photosynthetic: chlorophyll, phycobilin
  • Organic: Pigment Red 170, phthalocyanine, Phthalo Green, Phthalo Blue, Alizarin, Alizarin Crimson, crimson, Indian yellow, indigo, quinacridone, quinacridone magenta, woad.
  • Resin: gamboge
  • Polyene enolates: a class of red pigments unique to parrots
  • Other: hematochrome, melanin, Phthalocyanine blue, urochrome, Van Dyke brown

Inorganic pigments

  • Carbon pigments: bone black (also known as bone char), carbon black, ivory black, vine black, lampblack, Mars black
  • Cadmium pigments: cadmium pigments, Cadmium Green, Cadmium Red, Cadmium Yellow, Cadmium Orange
  • Iron pigments: Caput Mortuum, Prussian blue, oxide red, red ochre, Sanguine, Venetian red
  • Chromium pigments: Chrome Green, chrome yellow
  • Cobalt pigments: cobalt blue, cerulean blue
  • Lead pigments: lead white, Naples yellow, Cremnitz White, Foundation White, red lead
  • Copper pigments: Paris Green, verdigris
  • Titanium pigments: titanium dioxide, titanium white
  • Sulfur pigments: ultramarine, Ultramarine Green Shade, French Ultramarine, vermilion
  • Chrome pigments: viridian
  • Zinc pigments: zinc white
  • Clay earth pigments: sienna, raw sienna, burnt sienna, umber, raw umber, burnt umber, yellow ochre

See also

External links

All links retrieved November 18, 2022.

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