For a maximum assumed print size of 400mm x 500mm my current design calculations put the print time at 2.25 hours, this is a reasonable amount of time where the unexposed coating/emulsion will be waiting for exposure and the exposed emulsion will be waiting for processing.

So I've run a test, from a strip of paper coated with the emulsion I cut 10 strips (after drying) and over a period of 2.5 hours I exposed a strip every 15min. With a control strip that was left unexposed over the full duration. This gives a realistic test of the printing process where the exposed emulsion is waiting for up to 2.5 hours before processing.

The results show that over the time period in question (for temperature 24'C, and humidity ~60-80%) there is negligible variation in result. I ran the test in parallel with New Cyanotype test strips which performed similarly. It should be noted that Cyanotype requires double the exposure time to Kallitype, but is a print out method, so I don't expect any issues due to dark reactions. Which was my main concern with the Kallitype chemistry.

Palladium toned Kallitype test strips

Exposure time was 1:30s on my UV LED light box (395nm), paper was Arches Platine