Total Area Coverage

[K-naynay]

When Calculating TAC, are overall varnishes and aqueous coatings included in the percentage?

Example: Does a 320% area with a flood varnish = 420% TAC?

 

[meddington]

Quick answer: nope.
Longer answer: I've only heard the term used to represent the actual ink percentages in the separations/profile, and not including any coating.

 

[K-naynay]

So you’re saying that the proper way to communicate this to a customer would be:
320% TAC, plus over print varnish.


Is there any documentation out there that I could put on file to make this an official reference for our shop?

 

[meddington]

"So you’re saying that the proper way to communicate this to a customer would be:
320% TAC, plus over print varnish."

Might depend on context. If you're trying to communicate desired properties in file preparation (please provide CMYK with 320% TAC), the reference to coating/varnish might only confuse people. If your describing attributes of your printing, then that's probably fine.

 

[gordo]

Might depend on context. If you're trying to communicate desired properties in file preparation (please provide CMYK with 320% TAC), the reference to coating/varnish might only confuse people. If your describing attributes of your printing, then that's probably fine.

I agree with meddington, however, I would be very more emphatic about separating the two. 320% TAC only applies to CMYK separations, e.g. the values you see in PShop's separation settings dialog box.
Coatings and varnishes are not involved in TAC calculations.

best, gordo

my print blog here: Quality In Print

 

[rich apollo]

If you were working with Hexachrome, HiFi or other extended gamut processes then your TAC would be different, wouldn't it? For example Hexachrome uses 6 inks, so you'd have a potential 600% TAC.

Coatings and varnishes are exluded from TAC calculations, though.

 

[gordo]

If you were working with Hexachrome, HiFi or other extended gamut processes then your TAC would be different, wouldn't it? For example Hexachrome uses 6 inks, so you'd have a potential 600% TAC.

Not with Hexachrome because process color is removed where the extra colors are used during the separation process. I.e. Where orange prints, a percent of yellow and magenta are removed. Where green prints, a percent of yellow and cyan are removed.

Other expanded gamut methods like Big Gamut - CMYKCMY or CMYK + spot - keep the extra process colors tied to the midtones to avoid the problem.

best, gordo

 

[meddington]

When generating "hexachrome" profiles with ProfileMaker, you have two tac settings...one for cmyk (up to 400%), and one for all 6 channels (up to 600%). Not exactly sure how this works. I haven't tested separations from a profile generated
this way, but I would say (hope) that gordo is correct. It would make little sense to throw that amount of ink at paper.

 

[gordo]

When generating "hexachrome" profiles with ProfileMaker, you have two tac settings...one for cmyk (up to 400%), and one for all 6 channels (up to 600%).

Sorry, I don't know about what ProfileMaker does. Just what Pantone's Hexachrome separator does.

best, gordo

 

[otherthoughts]

Here's my 2 cents worth.

Linotype-Hell's, (presumably now defunct) foray into extended gamut separations called "Hi-Fi Color" was essentially the same as Gordo described for the Hexachrome technique, except that Hi-Fi color was setup to create a maximum of 7 colors, CMYK + RGB.

The intended purpose of the extended gamut was to address the RGB deficiencies inherent in the CMYK color space. The RGB deficiencies in the CMYK color space I suspect we can all agree, are not along the neutral axis. So in the case of Hi-Fi color, and I presume for Hexachrome as well, both techniques were purposely designed so that they did not extend into, nor interfere with the neutral axis.

As I understand it(leaving UCR/GCR aside for the moment), the maximum TAC value in CMYK printing occurs in the darkest shadows on the neutral axis and then tapers off from there. Extended gamut separations, never being designed to extend into the neutral axis as mentioned above, therefore should have no influence on TAC values.

The same technique described below by Gordo for Hexachrome, was also employed with Hi-Fi color.

With Hexachrome because process color is removed where the extra colors are used during the separation process. I.e. Where orange prints, a percent of yellow and magenta are removed. Where green prints, a percent of yellow and cyan are removed.​

So this leaves me with a question regarding ProfileMaker. Does ProfileMaker make any distinction between an extended gamut job and an ordinary 6 or 7 color job? It seems to me that it should.

Best Regards
Otherthoughts

 

[rich apollo]

Does ProfileMaker make any distinction between an extended gamut job and an ordinary 6 or 7 color job?

What would be "an ordinary 6 or 7 color job"?

 

[otherthoughts]

rich apollo - What would be "an ordinary 6 or 7 color job"?

Sorry, what I meant to suggest by an "ordinary" 6 color job was the standard CMYK process inks + 2 spot color inks that are unrelated to the image gamut space directly, as with silver and gold inks that do not interact with the CMYK inks for example.

otherthoughts

 

[slivingston]

Back to question about varnish with TAC

Back to question about varnish with TAC

Gordo - You have been the source of great info for me before. Right now we are having a discussion involving the situation bellow. We had a couple of jobs that the press had set off problems. One was printed on coated stock, the other on uncoated. The question was asked if TAC should have been adjusted when a varnish is being applied. I had never heard of this, but was looking for an answer. One of the posts had asked if there was any documentation on this and was curious about that myself as it would be nice to share.

Shawn

I agree with meddington, however, I would be very more emphatic about separating the two. 320% TAC only applies to CMYK separations, e.g. the values you see in PShop's separation settings dialog box.
Coatings and varnishes are not involved in TAC calculations.

best, gordo

my print blog here: Quality In Print

 

[Mike LaForest]

Slivingston : Are we being over analytical ? Could it just be a case of running too much Varnish?

Mike

 

[slivingston]

Slivingston : Are we being over analytical ? Could it just be a case of running too much Varnish?

Mike

Mike - It is possible that they are analyzing this too much. I am just a pre-press person, but I have never had this question brought up before. The question came from the pressroom manager, I would have assumed he would have known the answer.

Shawn

 

[Mike LaForest]

Being an old pressman I have "Bricked" my share of projects. After reading all the comments it still comes down to :
Loads too big
Running too much varnish I am assuming it was an overall flood
Not enough spray powder
But the comment on added driers should be looked into usually when problems happen as you describe it ends up someone added a press side compound that gives the opposite result then intended.