MF towels are used per product & put aside when that product application is completed. Always use a new towel with a different product.
I've had better luck applying sealants & waxes evenly with one of the MF-enclosed sponge applicators. Second choice would be a terry applicator.
IMHO, the MF seem to absorb less product than foam and, because you can really grab or "pinch" the MF applicator, I feel that I'm applying a thin layer of product with even force. The applicator is doing the work, not my fingertips applying pressure through the foam pad.
When I'm finished I put the soiled towels & applicators in a bucket of soapy water and squeeze them, working the soapy water through and, hopefully, remove most of the product residue. Then I transfer them to a bucket of clean water & let 'em sit until I accumulate enough for a small load.
I wash them in hot water (mine is 128*) with a bleach-free detergent and then I "wash" them again with no detergent to clean out all the soap residue.
Actually I'm just rinsing them but putting them through a full wash cycle does a better job via more aggitation.
I've noticed no determental effects washing them in hot water.
I hang 'em to dry 'cause they dry fast, then they're folded & put back in the Wal-mart Sterilite containers I picked up. They're transparent, stackable, and easily transportable (if necessary) ..... very handy.