Don't throw away expensive paint brushes—they can be saved!
Paintbrushes full of dried paint or varnish don't have to be thrown away. Done properly, it doesn’t matter if paintbrushes have been fossilized by oil- or water-based finishes of any type. You can restore any brush with a simple soaking in brush cleaner. A good soak in a brush cleaner can restore the bristles to almost-new condition. Here is how you do it.
Pick up a can of brush cleaner at your local paint or hardware store and pour some into a glass or metal container. Drill a 1/8-in. hole through the brush so you can suspend it on a stiff wire. The brush cleaner gives off nasty, flammable vapors, so cover the container with a plastic bag and set it in the garage or outside, out of reach of children and pets. After the brush has been soaking for a day or two, most of the paint will drop off it. Then pour brush cleaner in another container and slosh the brush around to wash out the remaining paint. Let both containers sit overnight. The paint sludge will settle to the bottom, so you can pour most of the brush cleaner back into the can, ready to rescue another brush.