I rarely use a paint finish on my sculpture. Unless it's absolutely necessary for the work, I generally prefer the natural colors of a material. My prefered material is stainless steel for sculpture because the surface can be left with a raw grind finish; no protective coating such as paint is necessary. In dry climates or indoors, a rust finish may be used on mild steel. One other finish I've used is very unique, a ferric oxide patina over stainless, which is a chemical patina applied with a lot of heat. This gives the zoo animal sculptures their warm tone.