I've got decals over twenty years old (and yes I still use them from time to time). Just keep everything sealed, out of the light, and outa sight and you should be fine. I occasionalyl look at my old kits that SOMEDAY I WILL BUILD (really), just not today Some of my kits are also 20+ years old and there are no problems with them either. The stuff I had sitting out on my shelves, some of it you could never tell it was white! Like TSP said, keep it shut. There's nothing like that "new kit smell!" - MT