Old grungy wax is a pain to remove - set the board out on a warm day and most of it will melt. When I've done repairs for guys who say "Fix whatever needs it" the first thing I do is clean all old wax off. If it's really a mess I charge 10 bucks or so.
Acetone doesn't work to dissolve wax. Coleman Fuel or paint thinner (mineral spirits) does. If used on a gloss coat there won't be any ill effects on the board.
Acetone will mess up an acrylic speed finish. Not sure about the other solvents mentioned. Probably best to spot test first.
…best wax removal: warm board in sun, scrape off wax, then residue gets picked up nicely by rubbing a few handfuls of PU dust into it(ie, shaping dust)…surpisingly effective…but wear a mask!!
I put em in the sun or use a heat gun with a plastic scraper to get the heavy stuff. I finish off with naptha and and old terry cloth towel. I get the naptha at Lowes and use it in my furniture shop. Great cleaner that wont harm a finish. Cuts wax and grease like butter.
I use this method. Warm in the Sun to soften wax. Scrape away as much as possible using a wax comb, windshield scraper, or rubber spatula. Then, I take an old white cotton atheltic sock turned inside-out and rub away the residue that’s left. An old terry cloth towel works, also.
I can understand if the guy is not involved with the board building, etc…
You just use a scrapper, a soft one to get rid of most then hot water, dish soap and a rag. With that you can clean ALL the stuff on a surfboard included tar stains etc
-If you work in a serious shop, the ding is cleaned with the wax scraper then couple of passes with styrene monomere.