Exposing a Screen
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There are many variables that influence how a screen is to be exposed. Some of these variables are: emulsion
brand, emulsion type, coating technique, mesh count, humidity, atmospheric temperature, and even the
light source itself. The Lumitron LED works best with pure photopolymer emulsion or film. The LED does work
with duel cure emulations and other diazo based products, but exposure times will be longer compared to
using pure photopolymer.
Step 1:
Properly prepare the screen to be exposed. The screen needs to be
clean, dry and properly tensioned.
Step 2:
Direct emulsion should be applied with a scoop coater, which is
available in a variety of sizes. The scoop coater should be able to fit
just inside the screen and be slightly larger than the image. It’s best
to use a sharp edge scoop coater, because the sharp edge pushes a
thin deposit of emulsion making it possible for fine details to be
printed.
Working under subdued light, fill the coater’s reservoir with room
temperature direct emulsion. Put the screen in the vertical position
with the print side facing out. Place the coater at the bottom edge
and tilt it slightly forward until the emulsion touches the mesh. With
even speed slowly pull the coater towards the top of the screen.
Stop pulling the coater about two inches from the top and tilt the
coater slightly backwards to let the emulsion settle into the reser-
voir. Repeat this process for the inside squeegee side.
It’s important to coat the outside print side first because it will leave a heavier deposit emulsion on the out-
side of the screen, which is needed.
Most likely, a small amount of emulsion will escape from the reservoir during the coating process and leave
thick deposits along the edge of emulsion. Just simply remove the thick deposits by scraping off the excess.
