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Through the Looking Glass

(May 2002) posted on Thu Jun 13, 2002

Learn how and why dirt affects exposure glass and how to keep it clean.

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By Mark A. Coudray

If you print large-format work and use extremely large screens (6 x 8 ft or larger), consider purchasing professional window-washer tools. These consist of professional grade, streak-free cleaner, a lambs-wool bar for scrubbing, and a high-grade window squeegee for drying. The whole set will run less than $20.00 and will also allow you to clean the exposure glass in less than two minutes.


You can also take preventive steps to reduce your exposure-glass maintenance time. Modern Solutions (608-222-2022) specializes in dust reduction in prepress areas. They make products like IMPRESS, which are used to coat the glass and repel airborne dust and dirt. The glass is coated once in the morning and then simply wiped with a special wand between exposures. The results are impressive.


Consumer products like RainX may also be used. This product is available nationally through automotive stores and is used to coat your windshield to prevent road dirt from adhering. Although this application involves vacuum-frame glass rather than an auto windshield, the results are the same and the product works quite well.


When you keep track of what kinds of dirt typically appear on exposure glass, it becomes easy to find ways of getting rid of the sources. Again, the main culprits are tape, blockout-tape adhesive, frame adhesive, old ink, and new and old emulsion. Tape adhesive comes from the frame, blockout tape, or tape used to position the positive. The adhesive often will ooze out onto the glass when vacuum pressure is applied during stencil exposure. If the tape is temporary, there is not a lot you can do. If it is permanent blockout tape on the mesh, you can seal the edges to the mesh to prevent bleedout. This is usually done through the use of a frame sealing compound.



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