I have several stashes of MFs, each dedicated to a specific job. When I am done using them I throw them in individual boxes marked like this: wash/dry; QD (this also includes things like Poorboys SW); leather and interior; glass; polish and glaze, etc. When I get about half a dozen in a box I throw them in the washing machine by themselves with no other towels or clothes. Each box of towels is washed separately so as to not cross-taminate (although I am wondering if this really is a big deal seeing how hot the water gets). I use Fab or some other liquid detergent with no bleach. If I use the dryer at all I fluff or air dry only with no fabric softner sheets. If it is warm, I simply hang them outdoors. If any get too dirty to be used again for the same purpose, I deligated them downwards each time to other jobs until they eventually get to the bottom of the pecking order - such as wheels. I seldom, ever throw a MF away. So far, so good!