Naptha is a mixture of straight chained hydrocarbon-ethers, straight chained alkanes, as well as some aromatic hydrocarbons. You can find some online or i would imagine certain hardware stores…James should know as he told me.
Yep, rubber cement from my experience actually takes a bite into the latex and becomes pretty much permanent property! I have used Plasti-dip over a few sigs in the past but I could see signes of it beginning to peel/wrinkle after lots of wear. It doesn’t bite into the latex as RC does, it sits on top. It’s still a good option though, especially if you don’t really wear your masks.
I sometimes spray it as Paul mentioned above but… you can even buy the cheap Elmers stuff and lightly brush over the sig with the included brush.