I don´t know, I didn´t knew what borax was, so I googled it and read about it. Here in Sweden there is a lot of strange rules.
Thank you for the info. I have several brushes with silver tip bagger and one synthetic. I clean them with Dove dIsh soap. I soak them for about a half hour in hot water. I then rInse and dry them on a clean dry towel. It seems to work well and there is no smell of new or any other funk. Your process seems to work very good.
I'm kinda late to this thread, but I have never seen the necessity to clean my brushes, be they boar, badger, horse or synthetic. Yes, I have tried the Oxi-Clean treatment, per the fellow at Whipped Dog on new badger knots I've installed. Most new natural hair brushes have some kind of odor, but it goes away quickly with use. I rinse my brushes after each use. I have never had a brush mildew, mold or "funkify" in any way shape or form, regardless of where I store it after rinsing and shaking and toweling dry -- bristles up or down, inside my cabinets or outside. The only brush I ever had that in any way seemed dirty when I got it was a recently acquired brand new monster Vulfix super badger with a 30-some mm knot that put out some brown coloring in the first couple of soap-ups and rinses. So what am I missing? Anybody else out there that has the almost total lack of the problems reported here?