Unusual dot gain chart

[LarryT]

A book printer supplied overall dot gain figures for a b/w job that will print on coated stock as follows:

1%-1.3
3%-3.1
5%-5.2
10%-10.3
20%-20.6
25%-25.7
30%-30.9
40%-41.2
50%-51.5
60%-61.8
70%-72.1
75%-77.3
80%-82.4
90%-92.7
95%-97.8
97%-99.9
99%-100

Note how the TVI increases continuously throughout the range, forming a straight line rather than a curved section when plotted as a traditional dot gain chart (see attached jpeg).

The printer confirms that 50%-K and 75%-K patches in a supplied pdf will indeed show up on the press sheet as 51.5% and 77.3%.

Is this believable? If so, any idea why a printer would want to set up their processes to get an overall linear tonal response?

 

[otherthoughts]

Perhaps he is re-inventing the wheel?

The dot gain numbers you were given are way out of line for sheet-fed and web offset printing in my humble opinion. My best guess is that he sent you linearization/calibration data for his CTP unit.

I once explained(about 12 years ago) to a very competent pre-press shift manager that his 50% dot would become a 68% dot on the press sheet and was a 68% dot on the proof he was matching the press sheet to as well.

He looked at me as if I had come Unhinged! He said, "How could printing possibly work if that were true???"

I assured him that it would be okay and that he should just relax, I would prove it for him until he was satisfied and comfortable that I was not "The Father of all Lies".

This man was very smart and talented but simply had not been acquainted with this particular facet of offset printing. Maybe the book printer is like this?

I suggest you ask the book printer if they could print a small test file for you in the trim margins or waste area of their next coated sheet press run. If they agree and you own a reflection densitometer, you could see for yourself.

If it's digital printing rather than offset printing? That's above my pay grade

Regards.
Otherthoughts

 

[LarryT]

Thanks for your comments, Otherthoughts. I'd agree that the best course of action is to independently verify those numbers. Good story.

Regards, Larry