All I know you need a good top coat on top of the decals to protect them. You are free to choose as long as the surface is clean and ready for the top coat. I think Singer spray coated on several layers of shellac, and the decals went on inbetween these. Singer might have used a different lacquer in the late 50s and early 60s. Cellulose types were common for furniture by then. The beige machines are probably enamel paint (like my aluminium 201K). I haven't had my hads on the a late machine with the black and gold finish.