A painting may be traditionally painted with oil or tempera on canvas or panel. Each type of paint has different technical possibilities and its own appearance. Oil paint often has a visible paint stroke, while tempera is matte, thin and very bright in color. The paint is usually applied with a brush. In acrylic paint, the pigment is not bound with oil, as in oil paint, or egg, as in tempera, but with synthetic resin. Gouache is an opaque type of watercolor. A watercolor is made with flowing, transparant paint on paper. Artists can use many other materials to paint with, using experimental techniques and on alternative supports such as cardboard, plastic, metal or stone.