The "Confederate Field Manual" (1862) says this:

"Preservation of Carriages

Wooden carrieages are preserved in well ventilated storehouses protected from the weather, or, in the field are protected by the sun by tarpaulin. They should have the paint renewed when it is worn off."

I'm pretty sure that I've read of a few gun carriages painted in other than the standard olive green because that was what was on hand, but I don't recall where. The CSA manual lists "olive paint" amd "black paint" among the battery wagon stores where olive is of course applied to the wood and black to the ironwork of the carriage.

The recipes for the olive and black paints can be found in the US "1864 Field Artillery Tactics" manual. Proportions follow, supposedly by weight.
First, "olive paste:"
Yellow ochre, pulverized 68
Lampblack 11
Boiled oil 37
Spirits of turpentine 0.4

Then "Liquid olive color"
Olive Paste 61.5
Boiled Oil 29.5
Spirits turpentine 5.5
Dryings 3.5
Japan varnish 2

Black paint is:
Lampblack 28
Litharge 1
Varnish 1
Linseed Oil 72
Spirits turpentine 1