Re: Press Profiling Question
Re: Press Profiling Question
- Subject: Re: Press Profiling Question
- From: Ray Maxwell <email@hidden>
- Date: Mon, 16 May 2005 11:00:35 -0700
Hi Dick,
I suggest that you start with a guess as to the dryback and print to the
estimated wet target densities. It will vary with the press, inks,
paper, and environmental conditions. I would suggest that a good place
to start is the following for coated paper.
Black dryback 0.10
Magenta and Cyan dryback 0.05
Yellow dryback 0.02
After you make wet and dry measurements you can calculate your own exact
dryback allowance.
I have tried polarized instruments and I believe that this introduces
yet another confusion factor. It introduces yet another spectrum
modifying device that does not help.
ANSI CGATS standards suggest the following standards.
Dry
Status T
Absolute
Black backed
I also suggest that you use a spectrophotometer. Densitometers with
filters that fade do not give consistent accurate measurements. The
spectro calibration methods allow for this.
Ray Maxwell
Busher Jr Richard C wrote:
I have been giving thought to the possibility of profiling a 4-color
offset printing press. I've noted that the GRACoL standards for solid
densities refer to measurements made when the press sheet is dry (I
suspect that SWOP and other standards have the same requirements).
However, in practice, one cannot wait until the sheet is dry to decide
if the proper densities have been obtained during the testing procedure.
The question then is what fudge factor does one use for dry down
changes in cmyk ink densities? Would you use a percentage of the
measured wet densities of each color? Or would you use a fixed amount
regardless of the measured wet densities of each color?
My goal would be to start the process at some industry industry
standard (e.g. 175 lpi screens, #1 coated sheet, GRACoL ink densities
and dot gain) and progress to stochastic screens, with elevated ink
densities.
Dick Busher
Cosgrove Editions
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