I have Champ decals that were probably printed in the 90's that are still good. However, they've been stored in a closet within an air conditioned house. Buying old decals off of auction sites can be problematic since you don't know how they've been stored. Any decal left in an attic for 20 years is probably no good. The last decals Champ printed have white labels with the contents printed on the label. Those have the best chance of being good. The ones that have the contents printed directly on the manila envelope are really old and are probably in poor shape.
Spraying an old decal with Dullcote or covering them with Microscale's decal preserver will help keep the decal from disintegrating, but I've had some old decals that I coated curl around their edges when applying them to the model. No amount of decal set would make them flatten out. Bottom line is if you can find the decals you're looking for in current production, buy those.
Ken
