Printer Transparencies?

[Zane Healy]

Here is a strange question.  Does anyone happen to know how long unused Laser Printer and Ink Jet transparencies last?  Do they go bad, or break down?  I have a stack of them, still in the boxes, a lot are unopened.  I scavenged them about 10 years ago, when people were getting rid of them.  

I wanted them for a Photography Project, that I’ve never had time to try.  At this point, I’d like to know if I’m wasting space storing them.

Zane