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Dimples and imperfections on UV-coated sheets.
April 16, 2008

 
Issue: Why might we be getting dimples and small imperfections on press UV-coated sheets? We are seeing this on sheets (see enclosed samples) that we coat, as well as on those we sent to a trade UV coater.

Comments: What I saw in your sheets was paper fiber and spray powder as well as some just plain dirt. All of those materials were probably on the sheet prior to coating. Keep in mind that if a sheet is going to be offline UV-coated, it needs to be very clean. This is accomplished by using air cleaners above the press, especially at the delivery.

In addition, very little spray powder should be run with a water-based primer. The UV coater should be covered when not in use. Also, a jogger aerator should be used to job and blow out the sheets prior to coating. Keep in mind that a jogger aerator should/must be vented to the outside. 

Readers, please e-mail your questions to Ray.  

Posted by Raymond Prince on April 16, 2008 | Comments (0)