Another suggestion...soak with dishwashing liquid (NOT dishWASHER detergent) in a large sink or your tub, agitate gently by hand and then rinse. Use coolish water as, yes, heat will set the stain. Don't wring the water out too much. Fold into a manageable size and roll in towels to absorb the bulk of the water then lay over a hand drying rack (if you have one or even the shower curtain rod to dry thoroughly once you're sure the spots are gone. This is how I've done my cross-stich and/or needlepoint for years. Tedious but it works. Good luck.