UV coating problem

[pun_lavor]

Hi there!

Yesterday, we had an interesting problem. We are in process of making a simple folded leaflet. The stock was printed on 135 g/m2 matte coated paper, 4/4 job, including standard matte offset varnish 1/1, applied in a very thin layer. The stock later went on partial UV coating, where the problem happened. UV coating was nice and shiny, but it was too easy to peel off (when you scratched it with nail for example). Imagine what would have happened if we later creased and folded the leaflet over those UV coated parts. Anyway, what do you think why the peeling of UV coating is happening? Is it because of poorly applied matte offset varnish and reaction with UV varnish? Just to mention, the stock dried for 24h prior to UV coating, and that we’ve never had these kind of problem with UV varnish. The supplier of inks and UV varnish stayed the same as before.

Thanks in advance.

 

[Albnn011]

Hi there!

Yesterday, we had an interesting problem. We are in process of making a simple folded leaflet. The stock was printed on 135 g/m2 matte coated paper, 4/4 job, including standard matte offset varnish 1/1, applied in a very thin layer. The stock later went on partial UV coating, where the problem happened. UV coating was nice and shiny, but it was too easy to peel off (when you scratched it with nail for example). Imagine what would have happened if we later creased and folded the leaflet over those UV coated parts. Anyway, what do you think why the peeling of UV coating is happening? Is it because of poorly applied matte offset varnish and reaction with UV varnish? Just to mention, the stock dried for 24h prior to UV coating, and that we’ve never had these kind of problem with UV varnish. The supplier of inks and UV varnish stayed the same as before.

Thanks in advance.

It appears to be a UV Coating incompatability. What did you print with? What did you apply the UV Coating with? We sell many types of UV Coatings for many types of applications. If this was a digital print, the toner playes a big role with adhesion properties with the UV Coating. You can call us at AL'S CO UV at 909-590-4142

Good Luck!

 

[Rhino]

You definitely have an adhesion problem which may be caused by a number of variables. We would need to dig deeper to resolve the issue. Please contact Rhino Performance Products @ 866-601-6241 or Welcome To Rhino Performance Products and we'll help you resolve this issue asap.

 

[pun_lavor]

Albnn011, Rhino,

Thank you on the offer. Since we are located in Europe, and already have a great supplier, I'll have to find another solution.

 

[JOHNYPRINT]

Do you think you might have used too much spray powder

 

[pun_lavor]

Do you think you might have used too much spray powder

Actually, we didn't. The amount of powder, was like for every other job. Today we varnished the stock once again (since the first time, offset varnish wasn't thick enough - the layer was just to weak), and UV varnish seems to be much better. Still, it isn't as it used to be, it keeps peeling off. I'm afraid what will happen during leaflet folding.

 

[uvdan]

UV Coating Issue

UV Coating Issue

How many UV lamps and at what power to cure the coating. Also, application method? Offset? Screen?

It sounds as though you may have over cured the coating and caused it to become brittle. I am not dismissing the adhesion issue possibility, either. There is a possibility of incompatibility between the varnish and the final coating.

One last thought- are you applying IR energy as part of the final cure to flow the coating?

 

[Sirmag]

UV Adhesion---

Two things to look at :
One being how the UV Coating was binding to the varnish..test uv to varnish
Two being the amount of Ink and Water--The new generation fountain solutions uses glycol as the ingredient to keep the reverse fonts open. Check the % and also make sure your inks are low to VOC free and wax free.

 

[pun_lavor]

uvdan, Sirmag,

Thanks for your reply. Today, we finally creased and handfolded the leaflet, and it came out better then we thought it will. Since the leaflet is designed to fold on the UV coated parts, on those parts UV coating slightly peeled off. However, the complete product looks sastisfactory.
It seems that the problem was between offset and UV varnish. When we applied offset varnish in thicker layer, UV varnish seemed to be better. I'm not excluding over curing, as the initial problem. (We do UV at partners print house, so im not familiar with details, but they use screen). Anyway, the problem is partialy solved, and thanks everybody for bright thoughts.