Please excuse me Technetters, but Mark Nowotarski of Advanced Atmospheres
Development Praxair Inc asked me for more info on the above topic, and I
haven't his address or e-mail to reply.

Are you out there Mark? Or can someone get me his e-mail please?

He asked about solutions regarding slump and atmosphere control of the screen
printer.

My reply is that it would be a good idea to control temperature and humidity
because pastes, particularly OA's, tend be more susceptible to change.

We had a case here in the UK with a customer who thought he was controlling
his humidity at 25% RH, but his meter was only accurate down to 20% at +/-
5%FSD. Our check suggested the level was actually at around 15%. It was cold
outside, at around 15degF, the factory heating was on full for the night
shift, and so the RH was very low.

This of course produced rapid drying on the screen rather than slump - but the
point is that the RH meter was not accurate enough and they rarely are!!

At the other end of the scale, OA's will be generally more susceptible to
moisture absorbtion because the ingredients will have a natural affinity for
more.

When all you want is an easy life, why not control the localised environment
to 65F, 25%RH at the low end, and 75F 50%RH at the other end. It won't cost
you as much as having the night shift stop production.

Graham Naisbitt
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