Following a rigid routine in your screen-prep department might give a false impression of consistency and organization. Roberts shares some tips to help you ensure accuracy in this important area.
Forming good habits in screen exposure
Our recent journey through the screenmaking process has finally brought us to the point of exposure. Our screens are now stretched with the correct mesh count, tensioned to the recommended levels, and allowed to relax and be retensioned until they become stable. The mesh is gently abraded and degreased and the emulsion applied in a manner that gives us a repeatable and accurate thickness. And it’s thoroughly dried, leaving no moisture to cause pinholes during washout. The graphics professionals check and recheck the artwork, and we are finally ready to expose the stencil. It’s then time to learn a little bit about what goes on when we draw down the vacuum blanket and turn on the very powerful UV lamp.
I only have a little more than a thousand words allotted to my column, so I will not explain the ins and outs of photochemistry this month. It’s actually not that complicated, and I am sure that your emulsion supplier will be more than happy to discuss the basics with you. I also know that your supplier has detailed instruction sheets that you should follow to the letter, and he or she should offer on-site training. Check past issues of this magazine for great articles on this subject—the ones you skipped in the past because they sounded too complicated. Take the time to understand what you are trying to achieve with the process, and you will soon be exposing to perfection. But first, make sure you have an exposure unit that is maintained well enough to expose a stencil perfectly every time you load in one of your perfectly prepped screens.
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