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printech, February, 2002
Re: Offset Print Sharpening


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From: Gary Jones (gjonesprinting@aol.com)
Date: Fri, 8 Feb 2002 09:33:32


Your inquiry to PNEAC regarding press problems including sharpening was forwarded to the Technical Inquiry Desk. From your description this problem could be pale exposure/developing. Check the exposure and development with a GATF Plate Control Target or a UGRA Plate wedge. Check for the proper solid step in the continuous tone step scale. Your plate manufacture can supply the correct exposure, most are around a solid 3 or 4.

Check the micro lines for resolution, usually the 8 or 10 micro line in the reverse part of the scale should be partly open. Also check blanket/plate pressures and roller stripes.

 Changes in the source water usually cause the fountain solution not to effectively dampen the plate and result in plate problems or ink/water balance problems. You should monitor your source water for changes in conductivity. Fountain solutions can be formulated to work with hard water, but variations in the water hardness will cause problems. If the water varies more than 100 on the conductivity meter, the variation can cause problems, and treating the source water is necessary.



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