I have used high quality china bristle paintbursh for various projects over the years. It was used for some exterior oil based paint, but mainly it has been used to varnish various hardwoods after they were stained (stain not applied with the brush). After every use, I clean it off with thinners, and spin it dry using a paintbrush spinner.
Recently I have noticed that the bristlse are getting stiffer and stiffer, from the base of the brushes up toward the end. I's say that the bottom half closest to the handle is completely stiff and the bristles wont move.
I tried soaking it in thinners for an extended period of time, but that did not break it down and free them up. Is there a good way to fix this brush, or has it just reached the end of it life? How do I go about preventing this, was it do to inadequate cleaning after use?