I have found some color references in the Ordnance Instructions for the U.S.
Navy, 1864 that may be applicable, at least to the ship's weaponry. The U.S.
Navy used a combination of lacquers and paints to cover a variety of metal and
wood surfaces. The lacquers would have left the cast iron in its natural dark
metallic gray finish. The Navy also had formulas for a black paint for metal
parts of gun carriages (and I would presume other metal surfaces on board
ship). The Instructions also have formulas for black paint for gun carriages
(mentioned as British practice) and olive paint to consist, in part, of 68
pounds of yellow ochre (pulverized) and 1.1 pounds of lampblack. Some other
parts of the cannon, such as the elevating screw and the compressors for the
carriage would have had a "bright" (i.e. almost chrome) finish.
Hope you find this helpful. Good luck!
A. J. Daverede
Lanham, MD
IPMS 33505