Cake makeup refers to makeup which must first be dissolved in water before applying. It is occasionally referred to as "Water activated makeup" but usually only when contrasted to alcohol activated makeup.
Cake makeup can be divided into two subcategories. Dry and Moist cake makeup.
Dry cake makeup is the more traditional cake makeup. It is usually applied with a natural sponge, or other large open-celled sponge. Dry cake makeup provides good coverage, and resists rubbing off and sweat. The finish is extremely matte. The first widely available cake makeup was Pan-Cake by Max Factor.
A newer form of cake makeup behaves more like goache, an opaque watercolor. The pigment is in a much more readily disolvable base which can be readily applied by brush. It dries bright and solid without being overglossy. This makes it a popular product to use in body painting. However, it's elastisity is only minor and can crack or flake under high stresses. For an improved hold, a fixing spray should be used. Popular brands include aquacolor by Kryolan.
When sufficiently dissolved in water or alchol, Moist cake makeup can serve as airbrush makeup.