Black shingle granules melted/stuck on Duradek

I was approached today(by a very large roofing/exteriors company) to remove shingle granules from new decks. Their roofers had left the small specs to melt on to the Duradek. The granules themselves can be picked off, but they leave behind a tiny mark (tar? Grease?). I have surface cleaners/4000psi, but my main concern is getting the grease/tar stains off, they are tiny but noticeable. Any suggestions?

I’ve never run across this problem before so I can’t give you a tried and true remedy. My only advice is to do some testing and try to figure out what will remove asphalt without damaging the deck.

I’m not familiar with Duradek. Is that similar to Trex?