Jeff: Actually TMax RS at working strength has a shelf life of about 6 months if stored in a full bottle. It is formulated to work well if it is replenished, so you might want to look into that possibility. You can download a PDF on the TMax developers at http://www.kodak.com/global/en/professional/support/techPubs/j86/j86.s html.(posted 8420 days ago)