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Old 03-16-2006, 01:49 PM   #1
PeterArnel
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Default Dot Gain

I really need help here - there is a huge debate going on as to whether printers compensates for the dot gain he gets on his press by reducing the dot on his CTP plate or whether he runs a linear plate - which is 50% digital dot = 50% on the plate and accepts the dot gain
If printers are lurking around or any one can ask their printer what they do I would appreciate it
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Old 03-17-2006, 12:57 AM   #2
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Originally Posted by PeterArnel
If printers are lurking around or any one can ask their printer what they do I would appreciate it
Oh dear, Peter, I do hope some more printers jump in here. I just do up my files and leave all that stuff to the printer!

   
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Old 03-17-2006, 02:38 AM   #3
don Arnoldy
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Originally Posted by PeterArnel
there is a huge debate going on...
IANAP, why is this a debate? if you *can* compensate for dot gain, why wouldn't you?

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Old 03-17-2006, 07:19 AM   #4
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The debate or research is that there is no standard for what the doit gain should be - It would be good if 50% digital dot = 50% on the paper - but this is not practical as we would never match previous work.
Some of us believe that there has to be a standard based around 50% = 64% CMY and 67% on the black -Its a real problem for clients who get work printed at different printers as the colours never match
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Old 03-17-2006, 08:23 AM   #5
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Peter:

there has to be a standard based around 50% = 64% CMY and 67% on the black

Since paper varies so much, and, of course, the printing method, isn't it a case of 'Suck it and see'?

   
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Old 03-17-2006, 08:27 AM   #6
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The debate or research is that there is no standard for what the doit gain should be …
This strikes me as a problem of new printing technologies. We used to be told that dot gain was an increase in dot size that could be blamed on (er, was attributable to) errors (er, variations) in contacting, making the plate, or mechanical differences with presses. Perhaps even differences in printing stocks.

Then, when imagesetters became a standard, it was sometimes blamed on exposure, emulsion, or whatever variations.

It never occured to me that dot gain might be a standardizable issue. In fact, as a designer (at least during the first 25 or 30 of the past 40 years), I was always told not to worry about it, that this was in the realm of printer expertise and related to the printer’s equipment and his experience with it.

Has all this changed somehow? Or do they know something today they didn’t know about dot gain 10, 20, 30, or 40 years ago?

I also remember that printers used to use textbook mathematical equations to determine the gain for a particular job. Are these no longer useful?

   
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Old 03-17-2006, 08:55 AM   #7
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The debate or research is that there is no standard for what the doit gain should be…
Continuing from my earlier message, I fell upon a copy of the 1992 edition of the Graphic Arts Encyclopedia (I can never find any book when I need it, but this literally almost fell off the shelf).

It more or less confirms my earlier thoughts, but also refers to the equations by which printers calculate dot gain in order to compensate for it: One is the Murray-Davis equation, the other Yule-Neilsen (which is a modification of the first).

Another thought: I had always heard that English printers used positive transparencies rather than negs as we in the States do. If so, couldn’t that also affect dot gain?

   
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Old 03-17-2006, 09:10 AM   #8
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… there has to be a standard based around 50% = 64% CMY and 67% on the black …
Not sure why, but I found another bookson this topic.

From Printing Technology (by Adams, Faux, Rieber; 3rd editon, 1988): The causes of dot gain include improper plate exposure or processing; improper ink and water balance on press; type and condition of the press; and paper and ink combination.

Seems to imply a somewhat controllable dot gain within a particular print shop, but not that any standard could apply everywhere. This book was written before imagesetters came on the scene, however. And it is definitely written about American printing practices.

   
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Old 03-17-2006, 09:24 AM   #9
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Originally Posted by ktinkel
We used to be told that dot gain was an increase in dot size that could be blamed on (er, was attributable to) errors (er, variations) in contacting, making the plate, or mechanical differences with presses. Perhaps even differences in printing stocks.
Dot gain is chiefly influenced by the viscosity of the ink, and the absorbancy of the paper. Chemical drying accellerators and in-line driers can reduce it too. Variations in the film/platemaking process also factored in.

For any press/paper combination, dot gain should be calculable--empirically, if nothing else.

I would be an unhappy camper (customer) if my 50% tint turned into a 65 - 67% tint.

   
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Old 03-17-2006, 09:27 AM   #10
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Dot gain is chiefly influenced by the viscosity of the ink, and the absorbancy of the paper. Chemical drying accellerators and in-line driers can reduce it too. Variations in the film/platemaking process also factored in.

For any press/paper combination, dot gain should be calculable--empirically, if nothing else.

I would be an unhappy camper (customer) if my 50% tint turned into a 65 - 67% tint.
Sure. But it does sound as if all the variables are within the printer’s control, and since they do not all have the same equipment, supplies, or practices, hard to standardize. No?

   
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