Anyone print with UV ink?

[ericheartsu]

We've been printing more and more with UV ink for our screened stickers, and it's pretty fun, but i'm always really concerned about the curing of the actual ink.

I was wondering if anyone on here has printed with it, and can give me a few pointers on curing? I've followed the tech sheets, and have that down pretty good, but i'm still concerned with being able to scratch off top colors and stuff like that.

So far i've used Nazdar, Dubitt, and polymeric ink. Polymeric is usually the easiest to print with, but i still have a lot of questions even after talking to my sales rep a bunch!

[StuJohnston]

Are you adhesion testing as recommended by nazdar? They should have a note in the tech sheet about it.

[ericheartsu]

yep, sure am, but that's part of my question on the curing.

the adhesion test is fine, but i can scratch ink with my fingernail, even after postcure

[StuJohnston]

Even with the tape and razor blade test? Huh. To be honest, I don't use UV, but I have been researching it for a while. One of the issues is that the lower layers cannot be fully cured, not unlike flashing an underbase before you go on to the next layer. From what I have read, it is totally possible that the top layer is scratching off due to the layer under it being over cured.

I would test out how little curing on the lower layers I could do without running into blocking issues and see if the problem persists.

This dude is probably a better source, http://bhargavmistry.wordpress.com/2010/02/17/how-to-maintain-consistency-with-curing-uv-inks/ From what he writes, post cure doesn't sound like something you want to do.This white paper also supports that idea, http://www.pneac.org/sheets/screen/UVCurableInk.pdf

In a way, I kind of like solvent over UV in this case because the top layer of ink will partially dissolve the lower layer with its solvent. There has to be a way to test this like you can with a exposure test for emulsion.

[ericheartsu]

Even with the tape and razor blade test? Huh. To be honest, I don't use UV, but I have been researching it for a while. One of the issues is that the lower layers cannot be fully cured, not unlike flashing an underbase before you go on to the next layer. From what I have read, it is totally possible that the top layer is scratching off due to the layer under it being over cured.

I would test out how little curing on the lower layers I could do without running into blocking issues and see if the problem persists.

This dude is probably a better source, http://bhargavmistry.wordpress.com/2010/02/17/how-to-maintain-consistency-with-curing-uv-inks/ From what he writes, post cure doesn't sound like something you want to do.This white paper also supports that idea, http://www.pneac.org/sheets/screen/UVCurableInk.pdf

In a way, I kind of like solvent over UV in this case because the top layer of ink will partially dissolve the lower layer with its solvent. There has to be a way to test this like you can with a exposure test for emulsion.

woah, this is insanely helpful

[ebscreen]

Ive seen (I think they're called) dosimeter probes, not unlike the Atkins thermo-probes, for pretty cheap.
Probably worthwhile insurance.

I'm envious, always wanted to print with UV, seems like it would make the headaches (literally) of printing
vinyl go away.

[Inkworks]

Get a UV cure-test puck, it becomes you're bible when doing multi color and even for checking proper cure on single color. Belt setting are a handy starting point, but UV bulb degrade in power over time and your cure rate will be changing along with them. The best point is not over curing the first few colors so subsequent layers adhere properly.

[ericheartsu]

Get a UV cure-test puck, it becomes you're bible when doing multi color and even for checking proper cure on single color. Belt setting are a handy starting point, but UV bulb degrade in power over time and your cure rate will be changing along with them. The best point is not over curing the first few colors so subsequent layers adhere properly.

Have one, and use it before and in the middle of every print. My problem is, is that there is 5% wiggle room in terms of the readings on it. Even though i get all the specs SUPER CLOSE to the manufactures specs, the ink still is scratching off, or not passing the thumb twist test.

[Inkworks]

Somethings goofy then. Is the ink fresh? Does left over ink go back in the cans after being on screen? Has the UV puck been calibrated recently?

We found you don't get quite the durability from UV that you get with solvent inks, but it should still be relatively tough and should stand up to standard adhesion tests.

Some more info might be helpful, what substrate are you printing on?

[ericheartsu]

Somethings goofy then. Is the ink fresh? Does left over ink go back in the cans after being on screen? Has the UV puck been calibrated recently?

We found you don't get quite the durability from UV that you get with solvent inks, but it should still be relatively tough and should stand up to standard adhesion tests.

Some more info might be helpful, what substrate are you printing on?

The UV puck was calibrated in Dec, we got it back in Jan. The ink does go back in the can as soon as we are done. We use Dubitt, Nazdar, and Polymeric ink, typically on 355 or 380 mesh. It's being printed on Ritrama #90 vinyl with perm. adhesive backing. usually either white or clear sheets. The Clear seems to cure fine.

I've been doing tests right out of the dryer, and post cure tests, and i'm still having trouble. I've also read that over curing the ink makes it so upper layers in multi cure will not dry correctly, so i'm wondering if that's where im stuck at now

[Inkworks]

Sounds like you're doing everything right, I'd call Nazdar and pick their brains.

[pwalsh]

Eric:  I apologize that I didn’t see your message earlier and offer up some assistance.  From what you are describing it’s possible that you are getting a “top-cure” on the ink and not curing the ink film all the way through.  There are two distinct components of the curing process to include; Milli-Watts which is the intensity of the light source, and Milli-Joules which is the overall amount of UV energy that the ink is exposed to.   

Top cure usually happens if you’re not getting a high enough Milli-Watt punch to cure all the way through the inkto the substrate interface.  I'd recommend that you drop an email to InkAnswers@Nazdar.com to get some more qualified advice.  Your message will be delivered directly to Nazdar's Technical Services Group and a specialist will get back to you with additional information on how to make sure that you are getting a full and effective cure of the ink film.

[ericheartsu]

Hi Peter,
thanks for responding! I've called the technical help a couple of times, and can't seem to get a clear answer. It's weird because my bottom colors cure just fine, it's just my top colors which seem to have an issue!

[Flying Colors]

We use Marabu for our UV ink.

Mark