Ok,,,, luff.... if you look at a strand of horse hair under a super high powered microscope, you'll see the hair looks like it has scales. By only playing without rosining will eventually clean the rosin from the surface of the bow, but small amount's of rosin still remain in the scale's of the hair. It's like having a hole in a piece of wood and putting wood filler on the wood then scraping it off, the remaining filler stays in the hole. In order to get a new complete surfaced you need to remove the old wood filler from the hole, same with rosin. Am I clear on that, do you understand my point?

Many year's ago, a man who raised horses told me that his horse's with white tail's and mane's, he used Corn Starch on the tail and mane to clean and whiten the hair. He also told me that's how they cleaned the "Budweiser" Clydesdale horses.  DOn't know how true it is but I can't dispute him, because I don't know for sure.

When I clean my bow's with alcohol, after they are completely dry, I only apply enough rosin until I get a nice smooth sound. Too much rosin is defeating the purpose, it rub's off on the string's and then you get the scratchy sounds.

I never clean my bow hair.  This way I have one more excuse.

Thank's SBV,, I've been saying all along to clean rosin build up with alcohol, but everyone want's to argue with me.