I inherited 4 merino wool sweaters and wore them to work last winter. I'd been hoping to score the thrift store find of the $5 merino wool sweater to wear while riding, but haven't found one yet. When I took 1 of the 4 sweaters out to wear this winter I noticed a big white stain on the sleeve of the navy blue sweater. I'm not sure what the stain is from and don't remember spilling anything on it last spring and am wondering if there is any other way to clean this without taking it to the dry cleaners. If the stain is permanent I would use the sweater for riding and would end up needing to clean it again later - how do people take care of those hard to find thrift store finds that the other guy always ends up with?