tacky printing paper sticks like brick

[nelsonba]

We run a 9985 Presstek 2-tower press, kompac dampening system, vanson inks, powder sprayer and infrared system. On some press runs the job is very tacky and sticks together like a brick. These are usually jobs with lots of ink coverage, or high volume jobs that are in high stacks off the press as they wait to be collated. They are so tacky that our collator/saddle stitcher (a bourg friction feed) cannot detect doubles.
Any suggestions of things to try on the press to prevent the "stick like a brick" problem?

 

[dabob]

I assume that you are using the powder system, and IR dryer properly, a good ink dryer and then short lifts 3 to 4 inches tall in the delivery would proably help.

 

[nelsonba]

We are using both powder and IR - problem with short lifts is the job is a run of 56,000 that has 4 sheets of 2-sided 11x17 offset. I don't think we'd have time to stop and off load 3-4 inches at a time. And it would drive my press operator nuts.

 

[dabob]

Racking

Racking

Its not so bad as you think . . . build some "L" bars from 1x4 stock or similar we have both aluminum and wooden ones and get extra press boards and just put a new press board in on the racks like in the photo below.

 

[Printdog]

There are a few things that will cause the problem that you are having. Too much ink, water, or cloged spray powder. The Kompacs put a lot of water in the system. The IR dryer drys out the ink on the second unit causing you to use more water to keep it from toning.Try not using that. Check to see if your powder is working. Spay powder will clog up if you don't keep it in a sealed container, humidity is a killer for spray powder.

 

[nelsonba]

Thanks for the advice on the Kompac and the IR system. We'll have to try using only the powder next time. Interesting to note if that isn't a good combination why were we sold the 2 units. What would be the purpose of a Kompac with the IR if they don't balance each other?

 

[rbailleu]

run a quicker setting or drying ink. run less ink. make sure your fountain solution has the minimum amount of chemistry to make it work. we run lifts of 5000 on enamel or offset with heavy coverage quite often and have very few issues. with an ir and spray powder. albeit not a ryobi.

 

[Printdog]

I think the IR system was not set up to work on long runs.It just gets too hot under the 2nd unit. My Ir dryer has not been turned on in 4 years. if you keep a close eye on the powder level and keep it dry it is all you need. Good luck

 

[Freeman A.Gain]

You also should check that you are using the correct powder. There are many who "claim" they are the best. I find that a coated powder is best, around 27 micron in size, but you can always try a larger size.
Best of luck

 

[BillJ]

It also depends on which powder system you have. The older style (Ryobi design) didn't do a good job unless the powder was fresh and dry. The newer system was an Airtech unit. The Airtech has a pulse solenoid that helps keep the powder moving and gives a more even coating. The powder unit can get clogged and the solenoids do wear out. In either case make sure to keep the unused powder in sealed container. The Airtech is designed to be used with a 25 micron powder.

Infrared units on that press are known for causing heat build up in the second tower. The IR unit mounts almost directly below the second tower. There should be a insulated heat shield that mounts between the IR unit and the tower. Even with the shield heat can still cause a problem in the tower.

 

[turbotom1052]

i would suggest in addition to all that was mentioned that you try not to exceed the total ink density that the paper manufacturer suggests. when printing 4/c process that toal ink density can be adjusted in your pre press dept. are you printing 4/c process in 2 passes on your press? you can usually get away with over 200% total ink density but id still be careful when approaching the total ink density recomended if you will be overprinting a heavy ink film on subsequent passes.