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Printreg, July, 2000
Re: low VOC blanket wash


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From:GaryJGATF(gjonesprinting@aol.com)
Date:Wed, 5 Jul 2000 13:54:31 EDT


Dave: I have not seen too many responses to your request from printers regarding their experiences with low VOC washes. In my experience in working with lithographic printers, low VOC washes are not popular. They have historically presented challenges in terms of ease of use, time required for cleaning, solvency, cost, and other performance measures, such as the wash leaves a residue or film that needs further cleaning. However, this does not mean that some printers have not had success in working with them. One of the key factors seems to be the ink system that is being cleaned. Those inks systems that are not complex, such as newsinks, seem to be more compatible with the low VOC washes. As one tries to clean the more complex inks, such as a sheetfed ink, the success diminishes. The other part of the challenge in formulation low VOC cleaners is the chemicals themselves. In order to reduce VOC content, as measured by EPA Method 24, you have to use water, water with surfactants, exempt compounds, or chemicals that do not readily evaporate at 110oC. Since litho ink is designed to repel water, water alone does not make for a good cleaner. Surfactants can interfere in the ability of the image area to attract the ink. Of the exempt compounds that could be used, they are not process friendly. For example acetone causes excessive blanket swell and introduces a fire hazard. This leaves those chemicals that do not readily evaporate at 110oC. Most of the ones being used a vegetable oil or vegetable oil derived chemicals, which do not provide great solvency and can leave films, residues, cause blanket and roller swell, and lead to press corrosion problems. Not all problems are related to technical concerns. We did have one member who quit using a low VOC cleaner, not because of performance per se, but because it increased their cleaning cycle by about double and it negatively impacted their ability to quickly change over the press for new jobs. You did not mention the type of inks being cleaned by the printer you are working with. Because of their type of printing and other process demands, they may not be able to reduce VOC content beyond their current level. Most of the major suppliers of washes have lower VOC content products. Have you tried any of them? Let me know how successful you are. Gary Jones Graphic Arts Technical Foundation 200 Deer Run Road Sewickley, PA 15143 412/741-6860 x608 - Phone 412/741-2311 - Fax



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