Weird tonal quality on uv web press

[mbwurtzel]

We have a Harris M110 4C Half Web with an end unit UV Dryer.

Images appear filled in, void of midtone detail and have an appearance of way too much GCR - and this could be the problem.

However, I think part of the problem, and possibly compounding the problem is the ink rotation we are running which is CMYK - really no joke.

In my 20 years this is the only time I have seen this sequence, typically it is KCMY.

Perhaps with UV inks it's different.

Is there anyone out there that has knowledge of proper ink rotation for a UV web press?

Thanks for your help.

MW

 

[jonprintz]

I think you have nailed it. The traps are not set up for the ink sequence the press is running. UV inks do not require a different sequence than conventional inks. Black ink is more difficult to cure. The black may be sequenced last on your press to keep that layer closest to the lamps. This will work OK on print jobs that do not have 4/cp but will cause you some problems when you do print 4/cp. Try running the same job with a normal print sequence and you will quickly find the answer.

 

[mbwurtzel]

Jon,

Thank you for the reply. Just out of curiousity, who do you work for and do run / supervise a web press?

 

[henrym]

jonprintz is right on the money, sometimes laying black last can kill a good print job.

 

[jonprintz]

Jon,

Thank you for the reply. Just out of curiousity, who do you work for and do run / supervise a web press?

MB,
I was a web press operator from 1988-2004 and currently work for a large printing company in Dallas, TX that has 3 web presses along with many types other print processes. I handle the R&D for all departments as part of my duties.

The problem presented above is not unique to web UV printing. The sequence issue will show itself when 4/cp is printed whether heatset web, conventional sheetfed, uv sheetfed, flexo, or screen. It can be overcome to an acceptable level but will take a lot of prep work. We have tried the black last sequence for curing reasons but do not normally run that way.

 

[green printer]

Just recently had a long conversation with a friend who runs a uv web press. They were experiencing most of the problems described here. He told me that they got this new product called UVIA added 1 oz to 5# of ink and all of their problems stopped immediately. We talked almost 2 hours and all he could say was he has never had UV run so easy. They no longer have an ink misting problem the pressroom's air no longer has the UV haze. He said that it is available from http://www.shop.bestchemsupply.com . He said the product is not on their store you must call or email.