Dot Gain

dkinsac

Well-known member
Hello Smart People! I need to understand what is what with a linear calibration and how much dot gain comes in to play and where! We are an offset shop with 4 four color presses. Currently using the same curve for all. I believe that you have to start with a calibrated platesetter and the presses in good running condition. (taking into account the sometimes hungover pressman) How do you keep it within 14 to 16 percent? Or is that even a good place to be? What are the variables? Paper? Tack? Ink? Humidity? Kinds of Ink? Please give me some input . . .
 
Re: Dot Gain

The dot gain on press for coated sheetfed offset is about 15-16% (K at 50%).

Gracol 6 and earlier assumed a prepress gain of 4-5% giving a total of 19-21%

If you calibrate your workflow for linear plates (ie 0% prepress gain), you total gain will only be 15-16%.

This can present a problem if you are using the traditional CMYK workflow. Most (if not all) of your images will be intended for a 20% dot gain and you will wind up with lighter than normal images on press. You will also have trouble with pantone process builds as the color books are also setup for 20-22% gain.

If you are new to this arena, I would suggest building dot gain curves to bring your out in line with the G6 specs. After you get you feet wet, you may want to start experimenting with G7 and an RGB workflow to maximize color quality.

....Wayne
 
Re: Dot Gain

Hi

You probably do this but thought I would mention it anyway. After you do the initial cal set from the plate reading, you should then put the plate(s) on each press and do a specific cal set from the printed paper for each press and adjust your original cal sets so you are adusting for dot gain on the plate.
 

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