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	"MY JOB DID WHAT?!!!!!!!!!!" -----SAID THE PRINTER BY RAY PRINCE The Printer is confronted with changing raw materials based on availability and price. There is no such thing as standard ink or for most parts of the industry not even standard colors or process ink. Standard paper does not exist due to variations in raw materials. If a job is to be finished, well it must be planned well with foresight given to the materials and process that will be used. In many printing plants regard for the requirements of finishing are not taken into account, thus many problems occur in the later process. Since I am a printer at heart I will be critical of printers and share the mistakes that are made. The mistakes (sure ways to kill a job): Mixing brands of process color ink can cause trapping problems as well as color reproduction problems because all ink brands do not print with the same amount of dot gain. Mixing brands of inks to achieve a spot color is a sure killer since each will dry differently and the inks may or may not have drier in them. Old ink - sheet fed offset ink that is over one year old, UV inks over 3 to 6 months old, and web offset inks over 6 months old should not be used since their print quality characteristics as well as drying characteristics will have changed. Ink really never dries all the solvent out of the ink but it will set. Do not confuse scuffing with drying. Ink will scuff due to the abrasive characteristics of pigment of mechanical abrasion in the press or bindery. If a job does scuff an over coat of water-based coating or varnish will help. Ink should set in about 30 minutes and "dry" in about 4 hours - naturally this will depend on the substrate, type of ink being used, and environmental conditions. Additives to ink are an old - time pressman's best freinds. It is amazing what is added to ink to bring out the desired quality. Kitchen chemistry seems to be the favorite. What should be added are ONLY those chemicals sold by an ink company for a specific purpose. About the only item a pressman should/or will usually add to ink is drier. Pigments are a problem for certain finishing operations - rhodamine red, reflex blue, purple, and metallics can cause serious problems with certain finishing operations. For the printer it is wise to check with the ink maker and finisher to see if any problem can be envisioned. Many printers will varnish or water - base coat a sheet prior to sending it for finishing with little given to how well a foil will bond to the coating. Some people say, "Why not test all the varnishes and coatings?" That is a most difficult job since there are approximately 50 manufacturers and many times that in coating formulations. The best approach would be to pretest the actual items prior to printing the job. When printing on plastics, testing the actual lot number of material is very important. These are some of the major issues I have observed over the years. Planning and testing are sound plans. Many printers say, "how did we solve that problem last month?" In reality they did not solve it. If they had solved it, the problem would not be happening again! About the Author: Raymond J. Prince is a senior technical consultant in the Technical Services Group at the Graphics Arts Technical Foundation (GATF) in Pittsburg, PA. A 43-year industry veteran, Mr. Prince conducts Technical Plant Assessments (TPAs) in responce to technical inquiries from GATF members and industry. As a printing specialist and troubleshooter, Mr. Prince presents technical seminars in plant training programs, and contributes technical information to GATF textbooks and Technical Service Reports. Reprinted by permission of Hot Stamp News Produced be API Foils, Winter 2001-2002