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Gapen on UV

Gapen on UV

By Darren Gapen

About Darren

Darren has worked in the printing industry for 30 years and spent more than 12 years at two of the nation's leading high-end commercial printers: Bradley Printing in Des Plaines, IL, and Williamson Printing Corp. in Dallas, TX. During that time, he operated conventional and UV 40˝ sheetfed presses and also successfully managed a $15-million pressroom equipment transition. Darren also was Lead Press Instructor for Heidelberg, where he directed specialty equipment startups and was involved in all aspects of the printing process by teaching both instructor and pressroom employees.

In addition, he served as a troubleshooter for various printing companies in the U.S., Canada and Mexico. As operations manager for a start-up specialty folding carton company, he played a key role in achieving more than $6 million in sales within two years. Currently Darren is president of D.G. Print Solutions, a consulting firm that supports printing companies of all sizes. He specializes in growth development planning, pressroom color management and pressroom training through specialty print applications.

 

Overcooked or Overcured; Both Can End with Unfortunate Results

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Here we are in the new year of 2010 and the holidays are now behind us. Most of us spent some time visiting family and friends. Probably eating and drinking more than we wanted to but we all know between Thanksgiving and New Years is not the most opportune time for us to start any diets.

How many of you had gone over to a someone’s house, spent the day basking in the magnificent aromas of a home cooked dinner being prepared in the kitchen? You just couldn’t wait to sit down for the meal. As the serving dishes were passed around the table, you filled your plate with all of those delicious looking sides and then came “The Bird”. You piled on the white meat. Once Uncle Buddy said grace, it was time to dig in.

You started filling your palette with all of those wonderful tastes of the sides and now it’s time to fill the fork with turkey. As you’re starting to chew, you quickly realize that your host has dried out the bird. Yes, overcooked and what a disappointment! You immediately scramble to find the gravy on the table and ask to have it passed to you. Now your white meat is swimming in a pool of brown sauce while you are wishing that someone would have taken the bird from the oven sooner, but you still complement the chef on her delicious meal.

Sitting with your family after dinner, you overheard some of your relatives sharing recipes and talking about the holiday dinners hosted in past years. Then you hear mention of the turkey and how it was left it in the oven an hour and a half longer than needed and a temp set 75 degrees higher than called for, just to make sure it was cooked thoroughly. Some folks tend to feel that more is better. Well it’s the same case in some pressrooms.

A total of 11 separate customer press OK’s, five sheetwise forms, a w/t cover and two days on press. The customer was ecstatic and all of the UV print and special effects look great. The job is still in the pressroom and on its way to the bindery.

As the folder operator starts to make ready the first form, he discovers the cracking on the folds. Havoc and panic start. They try to score the sheets first, though it’s printed on text weight stock. Is the coverage just too much? What caused the cracking? Well it wasn’t the coverage. It was the amount of energy used.

The four interdeck lamps and three end of press lamps were all set to 100%. This has not only stripped the sheet of any moisture, it has also overcured the UV coating which caused it to be brittle. The job looked great while it laid flat on the skids but then when folded, the sheets would give.

While running UV, you do take the risk for something like this to happen. Use only the amount of energy needed to dry the individual colors and check the cure of the coating when it’s coming off the press. If you wait until the job is in the bindery, it’s usually too late. There’s truly no reason to run UV lamps at 100%, just because.

And to those holiday cooks that want to overcook “The Bird” just to be safe. Follow the recipes. None of us want salmonella but most of us do love a moist turkey.

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COMMENTS

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Most Recent Comments:
joe kulis - Posted on January 14, 2010
Darren: Is there any way to check the UV coating to see if it is over-cured while on press? We have the traditional methods to check for adhesion and under-curing, but do not know of how to check for over-curing. Joe
dapo - Posted on January 04, 2010
HI Darren I have been there! Unfortunately some operators consider that if one turn on the wheel is good then two turns on the wheel must be twice as good. As we all know this is simply not the case. I have also seen overcuring of UV ink films cause adhesion problems between the ink and the substrate allowing fully cured ink films to be taken off clean with simple adhesive tape the bond was that fragile.. I have also seen, in the UK, zonal reconditioning units attached to the end of s/f presses trying to get some moisture back into the sheet post UV cure. Never really understood whether these units were very effective simply because once you have a fully cured UV film it is virtually impervious to water vapor especially at the sorts of pass speeds modern presses are using. Just wondered what your experience of these units was.
Darren Gapen - Posted on January 06, 2010
Dapo,

I haven't seen any of these units installed here in the states. I would be curious to see the measured results and the users thoughts.

Do you know any companies that manufacture these units?
Click here to view archived comments...
Archived Comments:
joe kulis - Posted on January 14, 2010
Darren: Is there any way to check the UV coating to see if it is over-cured while on press? We have the traditional methods to check for adhesion and under-curing, but do not know of how to check for over-curing. Joe
dapo - Posted on January 04, 2010
HI Darren I have been there! Unfortunately some operators consider that if one turn on the wheel is good then two turns on the wheel must be twice as good. As we all know this is simply not the case. I have also seen overcuring of UV ink films cause adhesion problems between the ink and the substrate allowing fully cured ink films to be taken off clean with simple adhesive tape the bond was that fragile.. I have also seen, in the UK, zonal reconditioning units attached to the end of s/f presses trying to get some moisture back into the sheet post UV cure. Never really understood whether these units were very effective simply because once you have a fully cured UV film it is virtually impervious to water vapor especially at the sorts of pass speeds modern presses are using. Just wondered what your experience of these units was.
Darren Gapen - Posted on January 06, 2010
Dapo,

I haven't seen any of these units installed here in the states. I would be curious to see the measured results and the users thoughts.

Do you know any companies that manufacture these units?