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. As a verb, painting is the application of paint. One who paints is called a painter. General painting services ranging from interior to exterior painting for commercial and residential service.
Paint is very common and is applied to almost every kind of object. It is a method of producing art, an industrial coating, a driving aid (lane markings), a preservative (to prevent corrosion or water damage), and has a myriad of other uses.
There are generally three components to a paint: 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.
Typical binders include synthetic or natural resins such as acrylics, polyurethanes, polyesters, melamines, oils, or latex.
Typical diluents include organic solvents such as alcohols, ketones, esters, glycol ethers, and the like. Water is a common diluent. Sometimes volatile low-molecular weight synthetic resins also serve as diluents.
Typical additives include pigments, dyes, catalysts, thickeners, stabilizers, emulsifiers, texturizers, adhesion promoters, flatteners (de-glossing agents), and the like.
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 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.
Other waterborne paints are emulsions 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 surfactants in the paint as well as hydrolytic effects with some polymers cause the paint to remain susceptiable 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.
Pigment
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.
Some newer paints - called prism paint - can produce effects where the color changes depending on the angle (orientation) at which it is viewed. Modern U.S. and 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.
Application
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).
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:
* 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
* it is possible to deliver very small amounts of paint or to paint very slowly;
* 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 brushes, paint rollers, 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: doing this with modern paints, which are highly toxic, might cause death or permanent injury).Rockville, Alexandria, Arlington, Fairfax, House Painters, Home Painting, Falls Church, Woodbridge Virginia, Manassas, Mclean
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.
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.
Paint may also be applied by flipping or spraying the paint, dripping, or by dipping an object in paint.
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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.
* 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 they are typically made using dyes exclusively (no 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.
* Anti-climb paint is a thick, non-drying coating for parapets, downcomers, pipes, window sills, fencing and walls etc. It acts as an extremely effective deterrent to would be intruders and burglars by making surfaces virtually unclimbable, whilst marking intruders hands and clothing. Coated surfaces appear normal but will remain unset and slippery a period of time.
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