EXPERTONLINE: NAPL Guru Offers Online Advice

Blogging? “How do I do that?” asked 40-year print veteran Ray Prince.

“It's short for a Web blog, and it's easy,” the staff of graphicartsonline reassured him. Prince was game. Here's a sampling of printer Q&As from his “Ask A Print Expert” blog.

Question: We're ready to step up to our first 40” 6-color press and are considering buying a used, 10-year-old press sight unseen, with no press test.

Answer: There is a difference between taking a calculated risk and a gamble. This sounds like a big gamble. Let's first consider your experience. Moving from small-format presses to a 40” is a big jump. If you were purchasing a new or a used press from a manufacturer, you'd negotiate or pay for training—both prior to installation as well as training onsite.

As for purchasing sight unseen and with no press test, this is a big-time gamble. I have seen so many 'deals' that were just plain junk and heartache.

If you need to purchase used, try to purchase a press five years old or newer. And purchase it from a reputable dealer or manufacturer. Press-test the press at its current location and then again on your floor.

Question: We are currently using a four-year- old densitometer for all density measurements in our pressroom. I hired a new pressman who says we shouldn't measure metallics with it. Is he correct?

Answer: Yes, he is correct. A spectrodensitometer will measure metallics accurately and, in fact, will measure spot colors accurately. The prices of these units are reasonable for the benefit.

Question: Why might ink be flaking off a plastic substrate we're using?

Answer: The dyne level is 44 for the stock this printer is using, which is considered correct for the substrate. When a tape pull test was done in both directions, the pull was excellent. When the material was creased or slightly bent, there is a discoloration – lighter. When tape was applied, the ink came off in large chunks. And when the stock was tightly creased, the ink flaked off.

This problem can be caused by many factors, but the two I would look at first are: Was the ink over-cured? Was it formulated for a little elasticity?

Question: Why are we having such a strong, nasty odor coming from our UV-printed products?

Answer: It is unusual to have an odor from fully cured UV ink or UV coating. If a full cure is not obtained, that could be your problem. I suggest:

• Have the ink company analyze the odor.
• Run the paper through the press with no ink or coating. Do you get the same smell?
• What is the wattage of the lamps? 300 to 400 watt lamps are the usual. I have seen one manufacturer installing 1000 watt lamps with problems.

Keep in mind there are several thousand presses with UV drying running every day with no issues. Odor is a rare, but unacceptable, problem related to any number of issues.

Question: How do I eliminate set-off when running polystyrene on a conventional litho press?

Answer: Set-off is a problem that most paper printers have learned to deal with, but plastic printers are still learning to deal with the problem. Polystyrene can be run successfully on a litho press without the use of UV inks if certain things are done:

1) An ink should be formulated for the plastic;

2) Run small lifts—about 3´´ high;

3) Use infrared cure to accelerate drying and setting of the ink.

4) Many printers like to add a drying agent to the ink. Many use Speedy Dry.

5) Once the load is removed from the press, take care not to jar the load.

6) Do not re-pile for at least 12 hours. Yes, this is being overly safe.

7) Don't forget to run spray powder.

Question: I'm looking for a flexo source to print and diecut large quantities of 1-color lobster bibs—90M, 180M and maybe 370M. Can you help me locate someone near Miami [FL]?

Answer:There are many fine flexographic printers in the Southeastern U.S. When checking with some of my friends, the firm Southeastern Printing in Stuart, FL, came to light. The owner is Don Mader, and their reputation is one of “a great company with good customer service.” Their phone number is 772.287.2141. I suggest you start there.

Question: I recently lost my experienced pressman. Should I sell a paid-for Ryobi 3302 and get an easy-to-run AB Dick that I can use with my poly plate system? Or, should I purchase a metal plate system for the 3302? (Metal is needed because the poly plates stretch.) The only thing I run on the 3302 are envelopes.

Answer: Most pressmen I've spoken with think the Ryobi 3302 is easy to run. But consider an envelope feeder, which can eliminate many press stops. And while polyester plates do stretch, I doubt you'd see it on an envelope unless you're running tight-register, 4-color work, in which case you shouldn't be using small format.

Question: We are a UV sheetfed and web plant experiencing poor dot structure and some background tinting on a continuing basis. We have tried three different ink manufacturers and two fountain solution manufacturers with no improvement. What should I be looking at?

Answer: UV has many advantages, but there is one disadvantage or negative item: UV inks love water. You need to drive water (i.e., fountain solution) out of the ink. The operating latitude is quite narrow for that type of ink.

With all that said, what you should do on one press is to invest in an Air Curtain system. There are several commercial ones on the market. This is a “linear fan” installed over the hard oscillator over the last ink form roller on the dry side. I have had 100% success with these units when an emulsification issue is present.