U of S | Mailing List Archive | alt-photo-process-l | RE: two questions about gum

RE: two questions about gum


Maybe you can try to alter the lightness channel of your image (convert
to Lab) before making the separations (go back to RGB after fiddling
with the lightness channel) using the "Levels" tool and setting the
gamma to a number over 1 - such as 1.2, 1.3, 1.4, 1.5; just try few
settings to see which one suits your workflow... If that works you'll be
able to print using the same curves and gum / pigment / dichromate
concentrations that you had calibrated individually before, but get a
lighter print. The idea behind making the adjustment in LAB mode is to
not change the color values...

All, what would you think about this?


-----Original Message-----
From: Marek Matusz [mailto:marekmatusz@hotmail.com] 
Sent: Wednesday, September 26, 2007 4:19 PM
To: alt-photo-process-l@usask.ca
Subject: RE: two questions about gum

I would say you should adjust your curve and not cut your pigments.
Cutting down on pigment will result in whimpy and grey looking print.
Adjust your curve so that you add ink density to the middle tones
resulting in lighter CYM printed layers. Longer development would help
as well. I like to have my negatives for tricolor gum to be a bit more
contrasty then they would be for a single coat gum and each layer when
printed somewhat ligher then for a single coat gum. Am I making sense
My 3c for the day
> Date: Tue, 25 Sep 2007 20:25:18 -0700
> From: kthayer@pacifier.com
> Subject: Re: two questions about gum
> To: alt-photo-process-l@usask.ca
> Charles, I'd need to see the print to say how much to reduce the 
> pigment. As a stab in the dark (so to speak) I'll say if it's 
> really really dark, then try cutting the pigment by half; if it's 
> just sorta dark, then a quarter.
> kt
> On Sep 25, 2007, at 6:57 PM, ryberg wrote:
> > Folks,
> > Since it is blown highlights plagueing me, I'll try again with 
> > reduced pigment. Any guess as to how much? Half? Quarter? Do 
> > you suppose I will need a new curve?
> > Thanks Charles Portland Oregon