It sometimes happens that you get dried masking fluid on your brush. I know Dennis suggests using lacquer thinner to remove it. But for those who do not have that available, you can used Vaseline! Good old petroleum jelly smeared and massaged into the brush helps you to remove the dried masking fluid. Then you wash your brush with Dawn. I read about this tip on an art forum and just tried it on one of my old brushes and it worked very well. Thought I would pass it along.