your films should not degrade over time.
Altho if you're using an alternative to film there maybe some issues. media could be easily damaged (water damage is the most common) or if using an inkjet, the ink could fade or run from sunlight exposure or humidity.
it's best to store your films in an envelope and try to keep them flat so they don't warp of get bent.
i worked with one print shop that used a cheap vellum that was not water resistant at all. They would not archive the films, just expose and throw away. They would always keep a digital file tho incase they needed to redo the job.
A forum community dedicated to T-shirt merchants, professionals and enthusiasts. Come join the discussion about graphics, commerce, dyes, prints, collections, guides, displays, styles, scales, equipment, accessories, reviews, classifieds, and more!