Soft touch coating.

[Freeman A.Gain]

We have been doing UV printing for the last couple of years with all kinds of different finishes and coatings. Lately we have had a real interest, by clients, in AQ soft touch coating. We had great success early. Super soft, one pass with a 7.5 BCM anilox roller. But recently, its been a struggle. Not as soft, slurring of the end of the coating blanket, and not very even. We have tried a 11.0 BCM anilox, lighter pressure on the roller to blanket, just kissing the blanket and then plus 0.005" under the blanket for slightly more impression. 20 seconds with a #3 zauns cup. Even tried heating it to reduce to 14.Nothing! Only thing that we can figure is a bad batch of coating, but our supplier swears other printers are still running fine. What now?

[67drake]

I run that coating around twice a month.
It seems like you pretty much covered everything I would suggest. The only other thing is make sure you stir the coating,and make sure down to the bottom of the barrel if running out of a 55gal. drum. Could your coating possibily have froze during delivery?

[keldrewett]

Blanket Durometer??

[Freeman A.Gain]

We have been using only small 5 gallon bucket, so stirrng is not an issue- we use a industrial mixer to start. The coating blankets that we used, are the same for every other coating job- UV,AQ,Special. Terribly perplexed.

[67drake]

A few other "shot in the dark" thoughts.
If running out of a bucket,is the coating getting alot of air bubbles in it? This has happened a few times to me while running speciality type coatings from a bucket, because our pump,lines,chamber hold about 4 gallons,leaving only 1 gal. in the bucket,so the coating is constantly being "churned" and pumped.
If so maybe combine 2 buckets in a larger pail,or try turning down pump speed.
Do you change the chamber blades often? I have seen oddball patterns in the coating when the blades wear.
Does press speed affect it at all?
Drier settings?
Could be a bad batch,or maybe the bucket got contaminated?
Can you pressurize your chamber? We do this on our UV coatings,but turn pressure off for aqueous coatings. The reason I ask is because I noticed that runnung too much pressure tends to distort the blades on the chamber,and they wear quicker.

[CKL]

I have better success with the HCB blanket from Macdermitt. Flexo type material 20% more transfer over a traditional blanket

[Freeman A.Gain]

All great suggestions, let me fill in some blanks. We always have 2 buckets of S.T. on hand for just that purpose, "foaming,air bubbles... whatever". We were given a heads up about that common problem. It's not so much of a problem with Harris & Bruno anilox roller system. We change the blades when they wear down- visual check, or leakage. The only time blades have given us problems though, are when they get a nick. We run the heat/IR/HAK normally at 95 degrees, but we've tried cooler and warmer; less IR, more HAK. Speed also seems to have no effect. Lastly, the H & B system is pressurize, we tried messing with that and the pump speed as well. Thanks 67drake, any shot in the dark always has a chance to hit the unknown.

Thanks for the knowledge on the McDermid blankets, CKL. We have recently been approached by a supplier with them. Just finding some time to test!

[arfamoe]

Have you investigated using a Peristaltic pump for the coating?

[cengland]

Justed started experimenting with soft touch today, been using gloss and satin coating with no trouble, put the soft touch in the press and now image is transferring to my blanket, is there a special blanket for this soft touch coating?

[Freeman A.Gain]

Not that I am aware of. If you mean your printed image is transferring to your blanket, that is a sign that you are not carring enough coating. I'm experienced in anilox coating units though. You need to use a larger BCM roller. What size are you using, if even you are using a anilox system?