Term: gesso: gypsum or plaster of Paris spread on a surface to make it suitable for painting or gilding (or a surface so prepared)
Broader: plaster of paris: any of several gypsum cements; a white powder (a form of calcium sulphate) that forms a paste when mixed with water and hardens into a solid; used in making molds and sculptures and casts for broken limbs | Unrelated: stake race: a horse race in which part of the prize is put up by the owners of the horses in the race