On the bottles recieved from Bostick and Sullivan it says 1 year for dry chemistry (how it comes) and 6 months for wet mixed chemistry.

When I was first learning how to do this process I used B&S mixed wet A and B Cyanotype solutions that were mixed at least 1 year before I used them. This was about 1 year ago and the prints from those sessions are fine..

So, I will be dangerous and go against what the bottles say and proclaim myself that I believe the cyanotype chemistry offered by bostick and sullivan can last at least 1 year when mixed with distilled water and stored in a dark place in a room that never gets any sunlight and doesnt get very hot or very cold.