To get it out of the engraving, you'll need to use aircraft stripper, and maybe do some digging with a graver or a dental pick. You'll need to strip it when it starts to peel on some of the smooth surfaces. The polished parts of the frame are slick, even when case colored, and that doesn't give the urethane anything to grab onto. If you don't rough up the surface (i.e., the metal), the urethane film will eventually disengage from that surface. Then you'll need to refinish it. Lacquer and TruOil are a better long term solution, in my opinion, and are easily reversible and renewable.
