Hello, i was just wondering how to properly clean a GW Towel, you know how sometimes you wipe to low and get a smear of dirt or some matter on a towel and it leaves a stain. well i just wash them in detergent with no fabric softner and i let them air dry. My question is that is there anything that you can use to try to safely remove the stain without affecting the performance of the towel? thanks alot Bob.