I remember reading about someone who was able to strip down an old Soviet set. I forgot what solution he used. I remember he said it was really toxic and had to do the work outside. I tried to find the thread but I couldn't find it. I found this other one. Perhaps you can DM the OP. See post 63 https://www.chess.com/forum/view/chess-equipment/where-can-i-get-soviet-style-chess-pieces-like-these?page=4.
Also, @Cgrau is an expert in all things Soviet chess sets. He could probably give you some background info about materials. Based upon what I read, @Greghunt is very knowledgeable about restoration work. There are a few others but I can't remember off the top of my head. Good luck!

Anyone out there familiar with this era of Soviet chess sets, their construction and finish, or how they were most likely making chess sets in the USSR back then? General or chess-specific wood finish knowledge and experience also appreciated. I have this set which I want to refinish; I just tested it with acetone to determine what kind of finish it is, and got no discernible result. I tried isopropyl alcohol too, with seemingly no effect. I would just like to know what I'm working with so as not to damage them further, because I adore the design of the pieces and it took me weeks of searching to find this set.
I saw some woodworking & finishing talk on these forums, so here's hoping someone who knows something will find this...
More info:
I just got a chess a couple weeks ago. It was purchased from an Etsy seller in Ukraine and shipped to the US. The listing didn't have any details other than the typical SEO word-salad. When it arrived, seeing it firsthand, I found that the finish on the white pieces especially is quite cracked (worse than you can tell in these photos, actually downright nasty in the cold light of day). Not to mention the felt pads look like scum, and the finials on the kings were cracked off, replaced with poorly centered plastic beads, and (I think) actually swapped onto the Queens. So, I don't feel guilty about tampering with them more as a little project.
Anyway, here are some photos. I know there are several different versions of this style/era of set—I've seen some variations in the shape of the knights—and I don't even really know what year it is from.
There's a confusing dateline which says OCT 13-39-80 as well as a separate stamp overlapping which looks like it probably says 1983.