Ask A Print Expert
A Graphic Arts Online blog that answers questions submitted by readers on key print production issues.
Shingling Packing
Question: My sheetfed pressman insists on shingling packing, is this correct? Answer: For older presses, shingling blanket packing is a very good idea. Basically each sheet of packing is cut a bit (1/8″) shorter than the next. The theory is to let the cylinder come to the gap gently. Does this work? Yes. Readers, to contact Ray directly please e-mail your comments here. ...... Read More
Comments (0)Looking at Color
Question: In our color booth I use magnets to hold the “OK sheet” on the back of the booth. Is this OK? Answer: This is absolutely the wrong way to look at an “OK sheet” to the current press sheet. Your eye cannot remember color thus looking at the back of the booth sheet and then trying to remember the color on the sheet that is in front of you is impossible. The be ...... Read More
Comments (1)Roll to Sheet – Sheetfed Presses
Question: I’ve been reading many articles on roll to sheet presses - what is the advantage? Answer: The big advantage is being able to purchase stock in roll rather than sheet form. This can be quite a savings. Likewise, if you already have a web this is a good way to use up miscellaneous rolls that may have already been charged to a job. Many printers find this a real advantage. The only ...... Read More
Comments (3)Mechanical Ghosting
Question: We have reprinted a job four times for ghosting and we still have it. What can I do? Answer: Having a two inch border around a 22″ x 20″ piece of art is really asking for mechanical ghosting. Since the customer is “always right” let’s look at what can be done. The first thing I would check is if the press has anti-ghosting rollers. If it does, make su ...... Read More
Comments (3)Ink Charge Distribution
Question: What is the right number for my press? Are all the units the same? Answer: There is no right number. You have to determine the number by doing dry solids and reading density every two or three inches lead to tail. What you would like is the high at the center and falling off to lead and tail. There should be no more than a .06 density difference between edge and center. Each unit more ...... Read More
Comments (1)Ink Canisters
Question: At Print ‘09 I saw many presses with ink canisters. Is this a trend? Answer: Yes, it is a trend and a very strong trend depending on the type of equipment and the type of printer. The advantage is savings of ink as well as better color consistency of ink due to the same amount of ink in the ink fountain at all times. Readers, to contact Ray directly please e-mail your comments h ...... Read More
Comments (1)Watching Blanket Costs
Question: Does it pay to try to fix/rejuvenate a used blanket? Answer: My answer would be rarely. Once you have a smash that is severe and the blanket is taken off the press, soaking in warm water or shooting the back with solvent helps only a little. As a general rule, toss the blanket. For UV blankets there is a company in Canada that will refurbish and clean UV blankets for reuse. They cannot ...... Read More
Comments (2)Sheetfed Press Speed
Question: Run slow, run fast, run at 80% of rated speed? What is right? Answer: For modern equipment made after 2007, most printers feel they can run at full speed. For equipment made between 2000 and 2006, generally what I see is 80% to 85% of rated speed. For equipment made prior to the year 2000, I would suggest a bit slower. Readers, to contact Ray directly please e-mail your comments here. ...... Read More
Comments (1)Automatic Defect Detection
Question: Are the new automatic defect devices worth it? Answer: Some are very, very good. If your work demands no or very few small defects, this is a way to tag the bad sheets. How small a defect you can detect is still being argued. One manufacturer states they can see a 0.010″ spot or void. Most printers would say this is a very large spot. Other printers want to eliminate small pin h ...... Read More
Comments (0)Measuring Durometer of Rollers
Question: How do I measure the hardness of rollers in and out of a press? Answer: For measuring rollers in the press, most printers will use the Rex pencil type Shore gauge since it is small and can be held at any angle - the vernier scale is the most liked model by pressmen. For measuring outside the press, most durometer gauges will work (Shore A scale) - please make sure if the model needs a ...... Read More
Comments (1)LED Ultra-Violet Curing
Question: I’ve been reading quite a bit about LED UV for curing ink - is it any good? Answer: Several companies are working on this technology and it has been shown at Graph Expo and Print 09 shows. My opinion is that it does show great promise due to reduced temperature and much greater lamp life. As the technology develops one can be sure the price will come down. I must admit the work ...... Read More
Comments (0)Ink Ball Roller Issues
Question: We are having great difficulty leveling off a solid on a large sheetfed press. What can we do? Answer: This is usually an issue that we see on older presses and not new presses. The photos of the ink fountain roller, when zeroed, showed that the ball roller, blade or keys are an issue. When the ink fountain is zeroed, the ink film should be even and light. You need a press mechanic. R ...... Read More
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