Good question WT. I'm curious too. I posted a similar thread many months ago, regarding preserving the 531 decal on my Gitane. Many here thought I was nuts for wanting to coat it with something. But it is cracked and starting to disintegrate. Though one member suggested clear lacquer was the worst thing I could try, I'm not so sure. The guy down at the local hobby shop suggested clear modeling lacquer for use over newly applied model airplane decals. I tried it and it worked, though not on my 531 decal. That said, I think I'd use one of the modeling clear acrylic paints made by Model Master or Testor's, etc. At your own risk, of course. I still haven't worked up the guts to try it on my Gitane.