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Printech, August, 2000
Re: blanket wash


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From:GaryJGATF(gjonesprinting@aol.com)
Date:Tue, 29 Aug 2000 09:25:49 EDT


Sherry: In response to your question about blanket washes, are they using the low flashpoint one for daily cleaning activities on blankets, ink rollers, or dampening rollers. The formulation for the low flash material would seem to be appropriate for cleaning metering rollers and other harder to clean press components where there would be dried ink, varnish, and other debris. The blanket wash with the higher flashpoint would seem to better suited for their daily cleaning. The wash with the lower flashpoint may be one of their favorite washes as it would appear to evaporate quickly. What are the vapor pressures of the two washes? In terms of recommending a specific blanket wash, there is not necessarily one particular wash that can be identified. Common blends that meet the low vapor pressure requirements suggested by EPA usually are a combination of aliphatic hydrocarbons, aromatic hydrocarbons and glycol ether. Since you are working with a newspaper type of operation, they may be able to use a low VOC cleaner, one with less than 30% VOC content. These washes are usually a blend of some solvent and a vegetable oil derivative. The success of these types of washes appears to be highly dependent upon the type of ink that is being cleaned and since newsinks represent the least complex ink formulations and in many instances, the blankets don't have to be as deeply cleaned, the use of low VOC content washes have met with some success. This does not mean that all nonheatset web printers can use these washes, it just that there seems to be some success and perhaps worth a try. Regarding fountain solution recirculation and filtration systems, they have shown to increase print quality, reduce print related problems, and extend fountain solution life. In terms of costs, it is difficult to provide this information. How is the system at the printer currently set up? Do they have recirculation units, do they have a central system or individual units for each press? The overall cost depends upon the size of the unit or units, number of units, refrigeration, etc. It would be best to contact several suppliers to get some bids and make the comparison from this data. Three vendors that come to mind are Procam, Royce, and Baldwin. Your question about fountain solution chemistry is a good one. There is more to fountain solution than just a wetting additive. While fountain solution is mostly water, it is a mixture of water and other volatile and non-volatile chemicals and additives that maintains the quality of the printing plate and reduces the surface tension of the water so that it spreads easily across the printing plate surface. The fountain solution wets the nonimage area so that the ink is maintained within the image areas. Non-volatile additives include mineral salts and hydrophilic gums. Alcohol and alcohol substitutes, including isopropyl alcohol, glycol ethers, and ethylene glycol, are the most common VOC additives used to reduce the surface tension of the fountain solution. It is also important to note that fountain solution must be formulated to be compatible with the ink as it needs to emulsify into the ink in order for the process to actually work. Also, fountain solution needs to be compatible with they type of dampening system used in the press and maintain its ability to function as the chemicals in the paper are introduced into it. Therefore, if any substitution of an ingredient is to occur, then it can't simply be replaced as it will change the chemistry of the fountain solution and the chemistry of printing. This is one the most important reasons why a printer is reluctant to change fountain solutions. If they want to use a different fountain solution, then the fountain solution and ink supplier need to work together to find a solution that will work with the paper being printed. Good luck on your efforts and let me know if you have any more questions. 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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