Muratic(or Muriatic) acid,I think,is watered down hydrochloric acid. I wouldn't use it myself, but the contact cleaner idea is good. The contact cleaner we had at my last job was a mix of freon and rubbing(isopropyl) alcohol. Rubbing alcohol itself is a good cleaner, and cheap. Just be careful around any printing. Personally, I do the minimal amount of cleaning necessary,to prevent damage caused by said cleaning.