need for spot coating

was wondering just how many of you guys are still cutting glue flaps out of coating blankets when laying down an aqueous coating that needs to either glue or that gets inkjetted mailing labels. Seems that there are alot of finishing places that still insist on no coating glue flaps and spot aqueous voids when ink jetting. I thought that with the new aqueous technology a prime coat could be applied overall thus saving the expense and time of cutting up coating blankets. Im hard pressed to understand why people are jumping through so many hoops to make things easy on the bindery when the technology exists to just coat overall. Am i missing something here or are finishers just being hmmmm whimpy???

 

You are missing one point
it is possoble to glue on any coating if you have the right glue system - PUR.
If you do , it's easy
if you don't ' it's hell and will not glue well

The issue is thet PUR systems cost big $$$$$$$$$$$$$$$
That's it

 

If you leave the glue flaps free of varnish the gluing will be far better than if you cover it. We, however, do use an emulsion varnish that we are happy to glue over. We did change this varnish once for a different make and it was a disaster, everything came apart. Your emulsion people should be able to help you find the correct grade. Just to add we would never glue over an ink duct sealer/varnish as they contain too many waxes and silicones for adhesion.

 

i know that many aqueous coating manufacturers make a primer coat that offers the adhesion needed to do follow up operations. I was of the impression that as long as you use the primer coat (WAX FREE) that you didnt need to cut a blanket for glue flaps. Now meny claims its all in the finishing. My thinking is that as printers we are forced to keep up with the technology with major capital investments in presses, ctp, ect. Why would a finishing company not be held to the same standards??? To have to cut a blanket @ app. 100 bucks a pop, not to mention the time required to do the actual cutting seems like an expense printers should be looking to work around. I think if your in the finishing biz it should be your responsibility to offer what ever it takes to be able to glue on top of aqueous. I think its time that printers hold the finishers to the same standards our customers expect of us!!! After all the biggest cost center in the entire operation from beginning to end is usually in the presswork.

 

Hi Tom,

If you use the correct emulsion you should be able to glue over it with normal pva glue, we had to try some different ones before we got the correct one. Speak to your varnish supplier and your glue supplier and they should be able to help you, it is possible. We use an emulsion on a rollercoat varnish machine for all our carton jobs without cutting the glue flap out.

 

now impacked you speak of the correct emulsion. Are you talking about a linseed based varnish applied through a printing unit, or an aqueous coating applied via a dedicated coating unit? The powers that be in my plant dont want to rock the boat and put pressure on our off site finisher when they say that they need cut out glue flaps. We just do it at a pretty significant expense. Of course we try to save all these cut blankets for future use but theres enough times where the layout or product is unique enough were we need to cut. I personally am getting sick and tired of bindery dept. and outside finishers dictating what we need to do on press to make their jobs easier at the expense of ideal pressroom procedures.

 

We use an aqueous coating online or offline without cutting glue flaps. From experience no duct/oil based sealer/varnish can be glued with PVA glue.

 

Where I am I can aqueous coat any sheet that has to be glued providing that the area that has to be glued has the ink knocked out. Its the wet ink underneath the coating that prevents the glue from drying.
You are right about how much we have to ***** foot around bindery houses. I have to run 130# cover short grain on a SM74 because they need it that way. Never mind the problems I have printing it.