The thumbnail version:
- It’s time again to consider the impact of summer humidity of your screens
- Humid weather requires special precautions before shooting screens.
The full version:
It’s time again to be aware of the impact of hot, humid weather on your screen room and to deal with it. You need to remember to take extra measures to dry your coated screens and then keep them dry. This is particularly applicable if you are in one of the regions of Canada where the humidity rises sharply in summer.
A must-have is a hygrometer which will allow you to monitor the humidity in the coated screen storage area. It should not be allowed to rise above 40% relative humidity. The reason is that dry emulsion-coated screens are susceptible to re-hydration. And this is to be avoided because if you shoot damp or re-hydrated screens, you will end up with the same effect as underexposed screens. Screens are only resistant to humidity after exposure.
You cannot underestimate the potential hassles if you do not dry screens properly after coating or if you allow them to re-hydrate before shooting. Pinholes, stencil breakdown, reclaiming difficulties, and ghosting after reclaiming, are all possible. And these are not the kind of additional problems you need in the busy summer season.
The solutions to this annual headache include dehumidifiers, exhaust vents, and air conditioning. In most cases though, a dehumidifier should do the job. And to be sure that a screen is suitably dry before exposure, a moisture meter can be very useful.