Aqueous Coating and Lab targets

[bebris]

Hello everyone,

We have Speedmaster 102-4-PL press with AxisContorl. There are targets defined in AxisControl to hit ISO standard and it is OK with most of jobs.
Problems are with jobs that has to be varnished with Aqueous Coating. Coating that we use (HI-COAT W2960 Matlak double sided) makes all colors less saturated.
If color bar is also varnished, AxisControl will try to compensate Aqueous Coating "effect" by adding more ink to the sheets. More ink will make high dot gain.

Question is: should we try to hit ISO Lab targets also with Aqueous Coating?
Or maybe we should NOT apply coating to color bar?

regards,
Juris

 

[venkatnagu]

Hello Mr.bebris,

This is venkat, take white reference on varnish area(with out any dust, scum) i think it may usefull

 

[Bob Onn]

Hi Juris
The rule is if you coat the job you must coat the colour bar and compensate for the dot gain. The colour bar uncoated will not be a true reflection of the job. Therefore, you will have a colour discrepancy between what is measured and the apprearance of the job
Bob

 

[rich apollo]

I guess this is a matte coating? Gloss coating generally makes colors appear more saturated.

Axis Control should be monitoring dot gain as well as density.

I think the first order of business is to establish if you can hit the ISO color targets with the coating. Then alter your plating curves to account for the resulting dot gain changes. And, as Bob said, if the job is coated the colorbar should be coated.

 

[bebris]

Hello everyone!
Thanks for your answers.

I guess this is a matte coating?

Yes, it is matte coating.

I think the first order of business is to establish if you can hit the ISO color targets with the coating.

We have set targets to ISO in our press. When coating is applied, AxisControl will try to get as close as possible by opening/closing ink keys. The doubt are that there is too much of ink under coating and printing so much ink makes process very unstable. Also dot gain becomes very high.

What does ISO says about coating? Does coated sheet should hit same targets as uncoated? Even when coating makes inks less saturated?
What is your experience what do customers require?

if the job is coated the colorbar should be coated.

Unfortunately sometimes this also is not possible. When there is so little space left on sheet we have to put color bar on very edge of a sheet. But it is not possible to apply coating to very edge of sheet. Then we have an option to apply coating partly to color bar or not to apply at all. I think partly applied coating to color bar will make measurements unpredictable. So in such case I guess we have only one option: to not to apply coating to color bar at all!

regards,
Juris