Here's a digitized picture of a photo I took using 35mm color film, in the small museum at New Windsor Cantonment, NY, back in the mid-1980's. The carriage is, I think, an original U.S.-made 6-pounder field carriage. Since it is at New Windsor, it probably came from the New York National Guard, but you may want to check with the museum. I cannot tell the exact period the carriage was made, since carriages of this general design were manufactured in the U.S. up into the 1830's, as I had one that was fairly complete including the iron straps which were marked "Washington Arsenal No. XX 1831" on the front.
The color of what I believe to be "original" paint appears to be light gray, with shade variation depending on the particular piece of wood you look at. However, since cameras and lighting can change things, if it is important enough, you may want to contact the museum and see if they have gotten a match to a standard color-comparator chart, or perhaps get one, send it to them, and request their help.
I'm looking for my photos of the incredible, original "wurst wagon" caisson preserved in the Morristown, NJ museum, since I can't recall how much if any original paint it retained.
As you can see, I tend to rely more on surviving specimens than written descriptions. How you figure out how centuries of oxidation may have altered the paint color, I do not know.
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