I have a Grumbacher 1 inch brush I have been using for over 15 years for glassing. I use it to apply finishing resin (polyesther or epoxy) for the final coat. I applies a flawless coat and leaves no streaks. If I recall correct, the brush cost 15 dollars 15 years ago. Regardless of which type of resin I use, the cleaning procedure is the same. First I squeggee the excess resin off the brush, then dip the brush in acetone, and brush (paint) off the acetone. Next, I use warm water and Lava brand hand soap. I rub the brush against the soap and work the lather into the brissles. I repeat this three or four times. Then I spin the brush between my palms to remove excess moisture, wrap it with a clean dry paper towel and let it dry. I believe I learned of this procedure from Harry Higleys "There are No Secrets" book.