The army had a very exact formula for mixing the print for gun carriages, limbers, caissons, & traveling forged. When the paint is fresh, it is an unattractive yellow green. With time, the paint matures into an olive green. With the effects of sun, wind & water, the color matures into a deep grayish green.
At Stones River NB, the original formulation was followed during routine maintenance of the living history artillery carriages & limbers. The initial shade was a bit off putting, smelt terrible & took forever to dry. Sometimes historical accuracy comes at a price. One extra treat was that any rags soaked with linseed oil could spontaneously combust. (I know someone who left a linseed oil soaked rag in a jacket pocket where it began to smolder as he was driving home.)
The battery wagon carried the raw pigments necessary to mix with linseed oil at need.