Re: Rethinking pigment stain

Katharine et all,

There seem to be a strong correlation between what as been called inversion
on this list and heat. With most test I've made with a 500W photoflood I got
inversion, as soon as I switch to a 150W plant growing lamp used at the same
distance all this inversion thing was gone. Is it only because of heat? I
don't know but beside the lower wattage the exposure time and all other
params remaind the same as for the 500W bulb.

Yves

----- Original Message -----
From: "Katharine Thayer" <kthayer@pacifier.com>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Wednesday, December 14, 2005 12:16 PM
Subject: Re: Rethinking pigment stain

>
> Well, I'm still going back and forth about this. I spent last evening
> re-writing my page on pigment stain to reflect a broadened definition
> of "pigment stain" including the tonal reversal as a special case, but
> you're right, there is that odd place where the paper is white, that is
> difficult to explain. Explaining it as fog doesn't work for me,
> because when I cut the coated paper in half and put half directly into
> water, I got the same pigment tone on that half as I got in the
> unexposed areas on the exposed half of the paper. To me, that's more
> like stain, and looks to be a function of excess pigment, even though
> it's not stain in the way I always defined stain before, as an
> indelible staining of the paper, because the sizing keeps it from
> actually sinking into the paper. I've only seen this effect with this
> one particular pigment mix (burnt umber) and don't have time to
> investigate it further, but I agree it's a puzzling effect.
> Katharine
>
>
> On Dec 14, 2005, at 8:25 AM, Joe Smigiel wrote:
>
> > Jack, et. al.,
> >
> > Works for me...
> >
> > I just wish I had a clue as to what was causing the shift. I wonder
> > how
> > many past prints I tossed because somewhere in the sequence of printing
> > a multilayer gum I inadvertantly introduced this reversal shift and
> > later thought it was an inexplicable random effect, that I didn't live
> > right, or was a bad person, etc. Glad to clear that all up.
> >
> > I'll be vary wary of using any black or neutral tint until I test it
> > for
> > this effect.
> >
> > Joe
> > ___
> >
> >
> >>>> jack@jackbrubaker.com 12/14/05 10:53 AM >>>
> > Joe,
> >
> > I think your definitions of fog and stain make sense in gum and are
> > consistent in other media. I agree we need a term for the effect you
> > describe below. How about calling it what it does (since we don't know
> > what
> > it is caused by). Using your words, "reversal shift" would seem to be
> > a
> > clear enough term for what is apparently a uniquely gum problem. Or
> > perhaps
> > "gum reversal shift" to make clear that it is just for gum.
> >
> > Jack
> >
> >> From: Joe Smigiel <jsmigiel@kvcc.edu>
> >> Reply-To: alt-photo-process-l@sask.usask.ca
> >> Date: Tue, 13 Dec 2005 22:36:20 -0500
> >> To: alt-photo-process-l@sask.usask.ca
> >> Subject: Re: Rethinking pigment stain
> >>
> >> The
> >> reversed areas shift about depending on the level of exposure, yet
> > there
> >> seems to be an intermediate exposure that leaves the paper white
> > without
> >> pigment stain. It does not appear to be a random effect although I
> >> can't explain it.
> >>
> >> Perhaps there would be a better term than "fog" to describe it, but in
> >> my opinion, it is not "stain."
> >
> >
Received on Wed Dec 14 12:04:49 2005