I am sealing the basement in my new 50+ years old house. I want to remove the old "paint", fill the cracks with hydraulic cement, remove efflorescence and scorch the concrete with muriatic acid, and finally seal the walls with a good water proffer. The problem that I have is that whatever is in the walls now, do not want to come off! In some places, it is nice and strong, in others the efflorescence cracked it out off the wall, and in others, it is brittle and falls off with a wire brush. I would like to get it all off the walls for a better grab, but chemical stripping did not work, and for the most part a wire brush didn't do a thing. Any ideas on how I can get it off the walls?