<P> Color - changing paints can also be made by adding halochrome compounds or other organic pigments . One patent cites use of these indicators for wall coating applications for light colored paints . When the paint is wet it is pink in color but upon drying it regains its original white color . As cited in patent, this property of the paint enabled two or more coats to be applied on a wall properly and evenly . The previous coats having dried would be white whereas the new wet coat would be distinctly pink . Ashland Inc. introduced foundry refractory coatings with similar principle in 2005 for use in foundries . </P> <P> Electrochromic paints change color in response to an applied electric current . Car manufacturer Nissan has been reportedly working on an electrochromic paint, based on particles of paramagnetic iron oxide . When subjected to an electromagnetic field the paramagnetic particles change spacing, modifying their color and reflective properties . The electromagnetic field would be formed using the conductive metal of the car body . Electrochromic paints can be applied to plastic substrates as well, using a different coating chemistry . The technology involves using special dyes that change conformation when an electric current is applied across the film itself . This new technology has been used to achieve glare protection at the touch of a button in passenger airplane windows . </P> <P> 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 watercolors and acrylic paints, became very popular with the development of acrylic and other latex paints . Milk paints (also called casein), where the medium is derived from the natural emulsion that is milk, were popular in the 19th century and are still available today . Egg tempera (where the medium is an emulsion of raw egg yolk mixed with oil) is still in use as well, as are encaustic wax - based paints . Gouache is a variety of opaque watercolor that was also used in the Middle Ages and Renaissance for manuscript illuminations . 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, also known as' designer color' or' body color' is commercially available today . </P> <P> Poster paint has been used primarily in the creation of student works, or by children . </P>

When did latex paint come on the market