There are wooden Riteways that might have shellac finish that would be removed with IPA or xylol (Sharpie). These would have been originally painted with the cured finish thickness factored into to spec for film registration. Then there also modern ones of plastic. These shouldn't have paint on them. Which is the OP looking at? Personally I wouldn't screw around with 4x5 ones if they're worn... Or if anyone painted and then sold them. They were expendable items that need to hold a spec precisely. When they're worn out, replace them.
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