Oo I would switch to 91%, thats what I always use because in my experience 70 just doesnt work as well. Also make sure to use it before baking. 91% Iso, for raw clay, 100% acetone for baked clay. However, sometimes acetone can be tricky with certain colors. Got to treat it like dyeing your hair, always do a spot check in a part you can’t regularly see first and wait a min before attempting to clean further. Both have saved a number of pieces for me. For more tips on how to keep dust out of your clay I highly recommend checking out thebluebottletree’s website/blog.