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ROLLER CARE

 
 
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Roller Re-conditioning
Veteran printers know from experience that rollers have to be in top condition to order to obtain top quality printing results. Reconditioning of rollers at regular intervals, not only maintains quality reproduction but also extends the useful life of rollers. Re conditioning includes removal of rule cuts when the operating diameter of the roller can be maintained by removal of case hardened ink, deep cleaning of the surface or precision grinding and polishing. Veteran pressmen know that a well-seasoned roller is better than a new roller.

Roller re conditioning, depends on foils frequency i.e. on how well the rollers are cared for. When the roller is properly maintained, re conditioning will be required less often. On the other hand, if the roller becomes dirty and glazed, if the dried ink is allowed to accumulate, then re conditioning is an absolute necessity as a "super wash-up".

If a regular roller wash-up, such the TRC Procedure is used on rubber rollers before the ink starts to dry, roller life will be prolonged and the hardening effect, minimized. If, the ink is allowed to dry on the roller, a more powerful roller wash-up is necessary. The various wash-ups tend to harden rollers more rapidly, thus requiring more frequent re conditioning by a roller manufacturer. However, even under optimum conditions, continuous wash-up has a tendency to harden the roller. Factory re conditioning will restore the roller, remove the outer surface and permit the natural plasticizers to return to their proper state.

For urethane rollers, regular use of the TRC Procedure wash-up is recommended, before the ink starts to dry. Hardening of the rollers is not such a problem with urethanes since most urethanes tend to soften over a long period. However, urethanes are somewhat susceptible to attack by wash up systems containing appreciable quantities of water and strong detergents. Extra care has to be taken to select a wash that is free of these materials

The hardness of rubber and other elastomeric materials is expressed in durometers. The durometer is checked by use of two different styles of gauges manufactured by the Shore Instrument and Manufacturing Company, Inc. Both push a stylus into the roller surface and measure the resistance. Our gauge is the pencil type; the other the quadrant style. Durometer is measured as Shore A hardness. A TRC representative will measure the durometer of your rollers.

Two to three additional points of hardness is not critical, but 5 to 6 point, is considered as problematic. Most authorities suggest 25 to 30 durometers for the ink form rolls. When carefully handled, they might go up to 30 to 35 durometers in a year; if improperly handled, the hardness might go up as high as 40 durometers. At that hardness, the surface of roller, for approx 1/32 of an inch in depth, may be as hard as 60 durometer and this is when the surface of the roller becomes slick and gazed. The only way to restore the roller is to properly condition it, since everything else is equal to a factory reconditioning.
 
 
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