Varnish Over Toner

[Manafaith]

Anybody out there running Ricoh equipment ever try to varnish after the job has been produced off of your digital?

 

[pippip]

I'd be interested to hear about this. Did a job last week which requested matt lam on outside cover and sealer varnish on inside.
As i suspected it was a litho quote previously then volume lowered for digital. Talked them out of it but my supplier did say it should be a problem for their varnish on digital.

 

[tpmar]

Anybody out there running Ricoh equipment ever try to varnish after the job has been produced off of your digital?

Not sure this counts as varnish, but I regularly U.V. coat the output from my 9100, both gloss and satin, seems to work pretty well. This is using a Morgana Digi-Coater.

 

[GOPISHANKAR]

for digital printouts the varnish liquid should be different grade , some times the varnish does not evenly spread out evenly on tints & for post press activities we have problem of paper cracking

 

[Manafaith]

We have had a problem with the varnish just kind of rolling off in the past but that was on our KM Machines. Guess we will just have to do some testing off of the Ricoh

 

[GOPISHANKAR]

pre heating the digital printouts before varnishing may get rid of the oils in the toner sometimes works

 

[Manafaith]

pre heating the digital printouts before varnishing may get rid of the oils in the toner sometimes works

Interesting.... I know a few years back that we would have to "burn off" some of the toner before we could UV the sheets. Might be worth a try

 

[GOPISHANKAR]

have seen better results on digital printouts varnished after a day of printing

 

[kev_24]

not sure

 

[tpmar]

Not sure this counts as varnish, but I regularly U.V. coat the output from my 9100, both gloss and satin, seems to work pretty well. This is using a Morgana Digi-Coater.

Looks like I may have spoken too soon. Was just trimming these business cards that I coated yesterday on our Digi-Coater using gloss Actega chemistry and this happened. Is this the kind of issue you were referring to Manafaith?

 

[Manafaith]

We have had that issue before with UV off of our KM Machines. I do know that each manufacturer has different coatings for different toner adhesion....at least that is what we were told. I know that we used to have really bad "chipping" issues in the past but we haven't tried any coatings since we installed the Ricoh. It kinda looks like your UV is rolling off?

 

[tpmar]

We have had that issue before with UV off of our KM Machines. I do know that each manufacturer has different coatings for different toner adhesion....at least that is what we were told. I know that we used to have really bad "chipping" issues in the past but we haven't tried any coatings since we installed the Ricoh. It kinda looks like your UV is rolling off?

Yeah that's what it's doing. I've coated a lot of post cards on 100# gloss cover with a lot less coverage than this and didn't have any issues. Sent samples to Actega, and our U.V. lamp in this machine is 9 years old so the first thing we're going to do is get a new lamp, I'll post if that helps or not. Thankfully the Ricoh toner is a lot more durable than the Indigo Electro inks so I don't think coating is going to be quite so critical.

 

[HRoss]

At the risk of posting something commercial, the issue is fairly common with toner based printing and UV top coating. There is a lack of intercoat adhesion between the print and the coating (or varnish) due to the toner oils sitting at the surface of the print. Many of the coaters are designed to use a brief shot of IR after the coating is applied, but before they are cured, to improve this intercoat bond. Each Printer company has a slightly different toner so my company, UV Specialties, has formulated coatings specific to a print engine to achieve this adhesion without the need for IR, except in the worst of cases. Even there we need less IR and this helps keep gloss high (with gloss coatings).

Bottom line, if you're not using any IR, try that and see if the bond improves (but watch for gloss drops). If not, look me up and perhaps I can assist. Again, my apologies for the sales pitch.

 

[tpmar]

I can now say with certainty that it was not the lamp. Just had it replaced and the problem is exactly the same. There is another post here in the forums talking about an issue specifically with Tec Lighting coater and chemistries. I gave this (see attached) to my tech to see if I can run Tec Lighting chemistries in this Morgana Digi-Coater. That's where I'm at for now on this, hopefully it gets resolved soon.

 

[ColorMonkey]

Just out of curiosity, is your UV setup where it has a heat lamp the sheet first passes through and then the sheet is hit with the UV lamp station. I ask because we had this same problem different coater but what we had similar problems and found if we "cooked the sheet twice then followed with the UV curing station it resolved the problem. We actually added a second heat lamp station to finally rid of the problem.

If your setup is similar to what I described take the sheet after it has been coated, send it through the heat lamps (not the UV section) send the sheet through a second time then let it continue to the curing station. As I said just curious to see what result you get.

We run Ricoh 7110 and 651 printers btw.
Good luck

As far as using varnish no such luck on our offset pressing applying to digital press work. Results of UV are far more superior in most ppl's opinions anyways.

 

[tpmar]

Just out of curiosity, is your UV setup where it has a heat lamp the sheet first passes through and then the sheet is hit with the UV lamp station. I ask because we had this same problem different coater but what we had similar problems and found if we "cooked the sheet twice then followed with the UV curing station it resolved the problem. We actually added a second heat lamp station to finally rid of the problem.

If your setup is similar to what I described take the sheet after it has been coated, send it through the heat lamps (not the UV section) send the sheet through a second time then let it continue to the curing station. As I said just curious to see what result you get.

We run Ricoh 7110 and 651 printers btw.
Good luck

As far as using varnish no such luck on our offset pressing applying to digital press work. Results of UV are far more superior in most ppl's opinions anyways.

That's interesting, as it is, the sheet goes between the applicator roller and impression roller to get it's layer of coating, then it immediately falls onto a belt that carries it under the one U.V. lamp. It's a really compact machine. Not sure if I can get it to do what you suggest but I'm going to give it a try, thank you.

 

[ColorMonkey]

Ah okay I see. So we had the option as well not to buy the flashing station, but we did. Problem was it didn't flash it long enough or really "cook it" for lack of a better term. Without that we experienced grief as well.

Here is a look at how our machine is setup and I noted the stations:

 

[tpmar]

Ah okay I see. So we had the option as well not to buy the flashing station, but we did. Problem was it didn't flash it long enough or really "cook it" for lack of a better term. Without that we experienced grief as well.

Here is a look at how our machine is setup and I noted the stations:

Thanks for the picture, now I see what you mean. I wish ours had that capability. In the picture I pushed the feeder away and it's probably a little longer than the coater. This thing has a really small footprint which is good for space but it would definitely be nice to have that pre-heating unit like you have. At this point we're looking into either a different brand of chemistry or a modified version of what we're running.

 

[_socket]

I've tried running digital through offset to put a satin varnish over the wax/glossy toner with never getting good results. The toner acts like barrier if there is heavy coverage and nothing bonds.
As per UV varnish sure you can get it to cure, but there is the infamous flaking problem no one wants to talk about.. Yes you can bake the sheet and get an ok bond that wouldn't flake per say by cutting, but a coin scratch would still remove it. We get acceptable results running 50ft/m and 75C IR.. But it's nothing like the bond you get when applied to a traditional ink sheet. Everyone has a "digital" Uv coating for specific engines that they claim "works". I think the raw physics of it is how do you adhere to silica and wax? I've tested most coating vendors in the market with just decent results. Nothing I'm be super excited about. For work with high coverage like a book cover I would highly recommend using a sheet lamination process for durable long term results.

 

[ColorMonkey]

Yeah success of UV coating varies dramatically depending on who you talk to and the machine/chemistry that's used as well as the toner that it's being applied to. I can say that as far as flaking goes we have not had issues with that although interestingly enough some papers when cut do produce some flaking on the bottom side of the sheets. In other words the top side of the cut is smooth but if you look under a loop there is a very slight curl down on the underside of the sheets. You can also see flaking or chipping as well. When UV'd it is only that much more obvious. This is heavily due to the type of substrate as well. We though UVing would help this effect however it does not as I said, just makes it more noticeable.

We UV covers for perfect bound/saddle stitch books and varies other material but I can say this and this is the only drawback I have noticed with this particular chemistry and that is, after it is handled a lot or just over time say 6 months or longer it does start to cloud. We have not had and negative customer feedback relating to this however is is something I have noticed personally.

Seems some ppl find a solution and some don't it is kind a pain that it is this difficult to find a solution for all digital work though.

BTW TPMAR I thought Ricoh came out with an inline UV solution have you looked into this? Not sure how well it works or if they followed through with it but if they did that might be a solution for you.