On Sun, 30 Nov 2003, Sandy King wrote:
>
> Sam's working method, which is based on a dichromate solution of
> approximately 3% or less in the final coating solution, with very
> short exposure times and with some of the most saturated colors I
> have ever seen in color gum, is compelling proof to me that it is not
> necessary to use saturated solutions.
Sandy: There is a verrrrrry BIG DIFFERENCE between 3% dry and "saturated
salutions." I haven't seen anybody insisting on saturated solutions. I
certainly don't use them.
My findings by the way for the most part agree with katharine's, tho the
tests of the weaker dichromates were so long ago I'd have to look for them
under about 60 pounds of whatever. That is, both the contrast and the
range were different with less dichromate.
However, her point about each concentration of PIGMENT changing the whole
equation, as well as change of pigment, is one I've tried & tried & tried
to make, that is being roundly ignored. To repeat, you'd have to do this
calculation for each combo to "standardize," and no matter what anyone's
inner scientist tells him, to "standardize" gum would be to tie both hands
and one foot behind your back.
One other point however... as I described at length in P-F #6, the LENGTH
OF DEVELOPMENT IS ANOTHER CONTRAST CONTROL. !!!! Only, it can work either
way. Long development can give more steps by rolling back the blocked up
shadows, or it can give fewer steps by washing away the top values. If
you've exposed hard enough, so the top steps don't wash off (a delicate
balance easier with higher dichromate) then odds are good for more total
steps, as I recall about 2 or 3 more in 18 hours.
AND ONE OTHER VERY IMPORTANT THING (NOTE THAT I'M SHOUTING NOW !!) DIGITAL
NEGATIVES PRINT SO DIFFERENTLY FROM CONTINUOUS TONE, I'M NOT AT ALL AT ALL
AT ALL SURE THAT SAM'S FINDINGS APPLY ACROSS THE BOARD. (Although
as I recall Katharine's negs are digital, but maybe a different digital.)
THE FACT THAT EXPOSURE IS EITHER "ON" OR "OFF" AND NO INBETWEEN COULD
ACCOUNT FOR RELATIVELY LITTLE DIFFERENCE IN EFFECT OF DICHROMATE
CONCENTRATION. BECAUSE THE PROBLEM IS MOSTLY HIGHLIGHTS. DIGINEGS HAVE AS
IT WERE NO HIGHLIGHTS... ONLY FULL DENSITY DOTS.
Judy
Received on Mon Dec 1 01:45:00 2003
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