It looks like Singer spray painted the shellac on the machines, at least they did at the UK factory ca. 1930. Something went wrong on your machine, because new decal sets work out well when refinishing older machines. Was it a pure shellac flakes solved in alcohol? Decals are very delicate and can't take much of anything, when the machine was new they were protected by a few layers of shellac.
I would use a type of real gold touch up paint if possible and almost any black lacquer paint for touch ups. It doesn't have to be high gloss if you plan to finish of with shellac on top. Shellac binds well to a dry clean paint surface.
Last edited by Mickey2; 02-13-2018 at 04:28 PM.