Sorcha described how to wash bowhair - it's the second post on this thread. It works, but be careful that only the hair gets wet. I've done this, it works OK. What's the damage to your rosin? Provided there's a bit big enough to hold you can carry on using it! In theory it's possible to melt rosin and let it set into block shape but I've never been successful. You need to be very gentle with heat, I used a water-bath. New rosin is quite cheap and less messy.