Dual-effect varnish

[Hannes]

Hi,

I would like to get information about dual-effect varnishing.
I had a trial few day ago and it didn't go well.

At first, there was almost no matt effect. And the gloss spots did not have very good gloss neither. It seemed like sheets were covered with primer varnish (low gloss) Now what went wrong?

Both varnishes are manufactured in the beginning of this year.
Waterbased varnish was shaked and stirred correctly.
Oilbased varnish was not stirred, but I believe it got mixed pretty good while putting it into the section.
We started with thin layer of matt varnish, then we added more and more, but the matt-effect did not go any better.

I would like to hear your opinion.

Best regards,

Hannes

 

[filipesousa]

Are you printing with UV or conventional varnishes?

 

[Hannes]

I haven't heard about Drip-Off varnishes to be conventional and UV.

The problem is with Drip-Off varnishes. I am sorry if I didn't make myself clear.

 

[Print Guru]

Hi,
1. I trust u r using varnish and coating from the same manufacturer - as they need to be able to chemically "shake hands".
2. The aqueous coating can be used as normal high gloss coating, so if u see low gloss on the non mat areas – either on the plain paper or on printed color - then this problem should be solved first without applying the "matt varnish" - just plain gloss coating.
3. Use 10% IR power only since IR conflicts with water aqueous coatings drying properties. Add hot air knife and extract humidity from the delivery area after the coater.
5. Does printing speed changes the mat-gloss effect?
6. for this effect u need to run 25%-35% more matt varnish in order to make room for the gloss coat to "diffuse in" into the matt varnish.

 

[Hannes]

The effect does not change when putting speed up or down.

at first we put matt varnish in and thought that it was not enough. Then we added more and more until this specific sound came from rollers (like there was too much varnish in). And still it didn't do any better.

Just in case I tell that there was about 97 % of matt areas and 3% gloss areas.

And yes, both of them are Flint Groups varnishes.

 

[Johnston Collins]

Not enough oil based matt varnish has been printed.
for the reaction to take place, there must be a significant amount of oil based varnish printed before the water based is printed on top.
i usually double the number on the ink ductor when printing the oil based.
overall waterbased will 'drip off' the oil varnished area.
if you are printing UV, do not dry the effect varnish after the printing unit

 

[Hannes]

no we are not printing UV.

I think we almost doubled the amount on oil-based varnish. At least I think we did.

It was our guess too that there isn't enough oil-based but as I told, the matt effect did not go any better when adding more and more oil-based varnish into the rollers.

 

[Print Guru]

Hi,

Does the gloss coat alone on glossy coated paper show high gloss or low gloss?

What kind of paper and paper finish are u using?

 

[Hannes]

The gloss itself didn't show as good gloss as we expected.

Paper was 150g gloss and 250g coated (matt)

And drip-off efect was better on the 250g

 

[Sureseal Tech]

Hi Hannes,
The level of mattness is dictated solely by the varnish on the particular substrate being used. If it is not matt enough there are certain considerations. Is the mattness being observed normal for this product within its specifications and film weight application. Applying more will help but an alternate matter varnish would be much better. Usually the varnish suppliers like to be present for the first trials of this type of product to evaluate the end result and advise. You should not have to apply as much to hear the tack splitting sound from the rollers where there is too much. It could be possible that this particular batch needs evaluating if it is nothing like you were expecting. The water based coating should be repelled by the oil based and show gloss in the relevant areas. Could be surface tension characteristics of the water based coating causing the problem if it is not wetting the non varnished areas. Not sure on that one without specs. Some suppliers supply a very high viscosity/high solids water based coating that requires heating prior to application to ensure optimum gloss. That said the water based you have should have shown some difference. Hope that helps in some way but without the specific items to hand it is difficult to comment more accurately. John Tierney.

 

[Rico]

Rico

Rico

Perhaps less varnish would help, it is a kind off trapping problem.
To much matt varnish is not always good, it is not a gloss varnish!!
What kind off cc coating roll you use?