Coating Brass

Q. Will a polyurethane help protect brass from toothpaste?

A. A true blooded two-component polyurethane might prevent tooth paste from staining brass, but I don't think the so-called polyurethane that you purchase in a hardware store will do the trick.

If you are a home-owner, please do NOT purchase the two-component full blooded polyurethane, because you need the proper protective clothing and respitrator to do this.

Getting adhesion between the polyurethane and the brass is the most important issue, and I can't immediately give you advice on this.