Factors affecting cure speed

In order of importance these are the factors that affect the speed your imagepac will harden:

i. The length of time bulbs have been on, bulbs level out output after a few minutes, the difference from cold to hot will be around 50%.

ii. Temperature- the external temperature governs the reactivity of the resin (this will be affected by around 30% from cold to hot) and also the light output of the tubes changes significantly as tubes give out more light out the hotter they are.

iii. The amount of open area on the bed, in typical exposure units with lower and upper lights, the light reflects around the negative bouncing back and filling in the floor, this affects exposure times from A8 to A4 negatives by about 25%.  Always black off around a negative to cover the lower bed with either the negative or black card.

iv. Cure speed of resin is the least important in how it affects cure speed.

Check that the negative is solid black as this could let light through and shorten the time or give you a narrow exposure latitude.