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Creatures of Habit in the Screenroom

(April 2008) posted on Tue Apr 01, 2008

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.


By Gordon Roberts

You should take some basic precautions every day to ensure a perfect stencil, regardless of whether you have a small tabletop exposure unit, a vacuum frame with a separate light source, or an integrated, all-in-one, wall-to-ceiling exposure unit. Some are obvious. Keep the glass clean and scratch free, and minimize dust in the workspace. Always use anti-static cloths and brushes after you finish cleaning the exposure unit to avoid attracting dust in the air onto the glass. Check the blanket every day for damage, and make sure that the vacuum is complete when it draws down prior to exposure. Now let’s look at some less obvious precautions and gain control over some variables that we regularly miss in the average exposure.

Purchase an inexpensive exposure calculator and learn how to use it properly. Ask your emulsion supplier to make sure you really know how to do the simple calculations necessary. You might even spend some money on a UV puck, which you can use routinely to verify that the correct amount of UV light is hitting the screen and the wavelength is correct for your particular emulsion type. Once you get a handle on these simple tests, you will be amazed to see how much variation there is in the ex-posure unit and that it cost you most of last year’s profits.

There are several reasons for variation in the exposure unit. The moment you expose a screen, you put the light source through some extreme conditions. The bulb shifts from room temperature to something approaching the temperature of the nose cone of a re-entering space capsule and then back to room temperature in a short period of time. It does this by being blasted with unimaginable amounts of high-voltage electricity, and every time you turn the light on, a little more incremental deterioration occurs in the quality and strength of the light source. Over time, you will need to adjust your exposure times to compensate for this.


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