To preserve your plates, the manufacturers recommend storing polymer plates in a constant humidity between 50% and 60%. At the very least, avoid extreme fluctuations in humidity. If stored properly (and cleaned correctly), your letterpress plates can last for one year or more.
- For your exposed plates, maintain a constant humidity by storing plates in a ziplock bag. Keep your plates away from ultraviolet light that will crack the surface of your plate (i.e. store in a drawer or cabinet).
- For your unexposed plates, store in a black light-blocking bag that is taped shut.