Shellac is a form of resin, I'm not all sure how it's made but it involves tree sap and a bug. How does artificually made resin difffer from the natural? I'm sure they used polishes and cleaners back when these machines were new, but I know most probably didn't. In my mind resin type polish could be ideal for these machines. As previoulsly mentioned I have tested on a few more or less worn machines, it didn't damage anything; paint shines up and decals was not affected evenin worn spots. I don't really know the list if ingredients in a modern resin type polish, nor how it will affect the shellac 50 years from now. My 201 was made in 1950, it's in fairly good condition. Even though I use this machine it's my aim to hand it over to the next owner in about the same condition as I got it, hopefully better; no missing parts and all working. The only way I have a chance at that is with a protecting polish.