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.
It will happen slowly over weeks, right? Wrong! I have seen brand new bulbs die within hours of installation, and I knew it because the results showed up immediately in an exposure test. Without the test, everything appeared perfectly normal. The light was turned on, the screen washed out, and then promptly broke down on the press. One of my customers found that he could never settle on a workable exposure time. He replaced bulbs and sent back defective units until he discovered that his air conditioner was draining so much power that it was causing brown outs in the screen room. All of his screen problems disappeared after electricians put in a separate circuit for the floor unit that he used. He’d have never known about the problem had he not been testing exposure. If you are underexposing or overexposing your screens, you are probably experiencing the following problems in your shop right now:
Pinholes I’m sure you’re blaming pinholes on the person who is supposed to clean the glass before every exposure.
Breakdown of the emulsion on the press You’ll blame the screen-prep person and accuse him of not abrading the screen properly or not adequately degreasing it.
Emulsion residue in the open areas of the mesh after washout This is unavoidable; nevertheless, you’ll blame the hapless person who you asked to perform the supposedly simple task of washing out the exposed screen.
Image is not crisp You’ll attribute this problem to the artwork and blame the opacity of the film or the skills of the poor fellow who produced it.
I could go on, but I think you get my point. Here’s your chance to be a hero by clearing the names of the employees who’ve faced false accusations and finally place the blame fairly and squarely where it should be placed. Find the exposure calculator, and start using it every day. Meanwhile, I’m going to stop typing now and have a doctor look at my blisters.
Gordon Roberts has a history in screen-printing production management that spans more than 25 years. He has held supervisory positions in shops that represent a broad spectrum of application areas and markets, including printed electronics, apparel, signage, and retail graphics. Roberts has presented training courses on the basics of screen-printing production and on shop management for the Screentech Institute and is presently a consultant for the screen industry. He can be reached at firstname.lastname@example.org.
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