~~~ of the plaque (w or w/o a lunette) will darken with some types of plastics, the plaque may not be warping or cracking. Here is an example of one piece turning about 27 years after the first picture taken. Collectors have often asked me through the years why did they make all those plaques so dark... and, of course, we know that wasn't always th case... Yet, with all this being said... there are plaques in some collections that look as new as they did when they were first made in 1925... That's the reason I stress about reading the notes about proper storage.