I purchased a thinbrick to match my exterior brick so I could brick a wall in each bedroom only to find that the finish is powdery and will come off over time. Is there a way to seal brick so it isn't forever-dusty? Washing it will help, but I don't think it'll solve the problem completely; plus it changes the personality of the brick.

While I'm at it...how would you prep the wall to ensure a long-lasting result?

Thanks in advance for your advice.