also change depending on viewing angle, using iridescence, for example, in ChromaFlair. Art 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, new water-based paints such acrylic paints, entered the market 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 common in the 19th century and are still used. Used by the earliest western artists, Egg tempera (where the medium is an emulsion of raw egg yolk mixed with oil) remains in use as well, as are encaustic wax-based paints. Gouache is an opaque variant of watercolor, which is based around varying levels of translucency; both paints use gum arabic as the carrier and water as a thinner. Gouache is also known as 'designer color' or 'body color'. Poster paint is a distemper paint that has been used primarily in the creation of student works, or by children. There are varying brands of poster paint and depending on the brand, the quality will differ. More inexpensive brands will often crack or fade over time if they are left on a poster for an extended time. Application Paint can be applied as a solid, a gaseous suspension (aerosol) or a liquid. Techniques vary depending on the practical or artistic results desired. As a solid (usually used 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 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 object being painted). This is called "powder coating" an object. 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. This is called "spray painting" an object. The reasons for doing this include: The application mechanism is air and thus no solid object touches the object being painted; The distribution of the paint is uniform, so there are no sharp lines; It is possible to deliver very small amounts of paint; Painting multiple