problem printing on aqueous coating

[oharek]

I am having problems printing on card stock (greeting cards) with an aqueous coating on one side. We have multiliths 1250 and 1650(2nd color t-head) with Kompac dampeners. We are using an AB Dick/Presstek 2340 digital plate maker and their Megapro (Itek) polyester plates. Oil base inks and Itek Mega fountain solution 15-1.
The copy looks washed out on the aqueous coating but the copy is perfect printing on the uncoated side of the stock.
We have had a technician from the ink manufacturer come in and he recommended different fountain solutions and a different formulation ink they make but the results were the same.
Has anyone come across a problem like this and can make some recommendations?
We also use electrostatic paper plates and chemistry for some of our work and have no trouble printing on the aqueous coating.
This leads me to believe it is the chemistry but don't know what I should try.

 

[John LaMantia]

The coating you are trying to print on has silicone/polymers/waxes etc. which makes for high gloss and rub resistance. Not much compatibility when printing on it. Ink jetting is an alternative but that may prove marginal as well. Try sizing the print area and then print on top of the sizing. That will work. Good Luck. John.

 

[jodiego7]

When you print on something that's coated all kinds of problems can arise. On AC coated products I have found that using Van Son "tough tex" inks are best. Run this ink and make sure you cut your water way down. Remember, you are printing on something like plastic. Once the material was coated before, it now has very little poruos properties, meaning the stock will not absorb the water like normal "paper" will. Also, remeber to spray the job and pull out in very little lifts. The tough tex dries by oxidation, not absorbtion so only time will cure the ink correctly....but it can be done. I do it all the time.

 

[FFR428]

Ditto on the tough tex inks. You need an oxi bind ink that dries by oxidation not by absorbsion. Be sure to crank up the spray powder to avoid offset and remove in small lifts. Using a offset powder with a larger micron range also helps.

 

[turbotom1052]

this might be the time to call in your ink supplier or coating supplier for some recomendations. they know better than you could tell us whats in their product and how to use it. it would be a shame to try overprinting a job on coating and have the job never dry. my thinking is that modern coatings have a lower wax component than the older coatings but there is really no way to be sure without talking to the coating manufacturer. the suggestions to use a full oxidizing ink is for sure something you should do and im thinkin that the ink should have a very high solids content. the other recomendations also make sense too

 

[jtdoonz]

printing on top of aqueous

You seem to have a problem getting ink to lay on aqueous as well as worrying about the drying. If you have any trim areas, try to put a decent size color block for take off to keep the ink flowing to prevent emulsification. Like the others said you have no absorption because of the aqueous so you need a oxidizing ink. We have over printed aqueous on large presses but we could just re-aqueous on that same pass. You'll never get the ink to lay down perfect, it has no tooth and you,ll most likely have a balance issue. Some mail houses are equipped to print on top of aqueous coatings. We would have to knock it out for some but others had the capabilities to imprint on the coating.

Good Luck,
jtdoonz

 

[chiricuzio]

On a related topic, we are looking for an aqueous coating that is highly receptive to imprinting on a DigiMaster black laser device as well as on HP Indigo presses. In the past we have had little luck with adhesion and scuff resistance, wondering if anyone has a source for a different formulation of Coating that eliminates this issue....

 

[turbotom1052]

a primer coating is gonna be your best bet because of its wax free or low wax composition. Its the wax that makes for the poor trap.