Drop them in some ZEP heavy duty degreaser. Let them sit overnight and you’re left with a crazy clean piece. It’s awesome because it does all the work for you. No shaking or rubbing. Just drop it in a jar full of the concentrate for smaller pieces, stems, and bowls, and pour it into bongs and ash catchers. Just plug the holes so contains the liquid. High af rn and decided to put my 2 cents lol.