From: Katharine Thayer (kthayer@pacifier.com)
Date: 08/17/03-02:22:07 PM Z
Christina Z. Anderson wrote:
>
>
> > > I. Degraded Highlights
> > > A. Insolubilization of the gum/pigment on the paper
> > > 1. Insolubilization due to light exposure
> > > a. Fogging or accidental non-image exposure
> > > b. Overexposure
> >
> > Did you test these assumptions ? For instance, I dried coated prints for
> > 1/2 hour IN ROOM LIGHT, and found NO extra pigment stain... though more
> > dichromate stain. Although a too thin negative may well "fog."
>
> I've been using room light and have no fogging. It'd have to be accidental
> exposure stronger than roomlight. But technically, how can we know whether
> it is fogging or just too much exposure?
> >
> > As for simple overexposure with a reasonable negative, longer development
> > will clear it. And in the normal course of printing, unless you've heat
> > dried or gone to lunch & left the light on, or left a coated paper at room
> > temp to "age,"there rarely is such a thing as "insolubilization."
> > Judy
> >
> I've had enough prints where longer development did not clear. In fact,
> there were some I left for 24 hours in the water, hoping.... So
> insolubilization is definitely a factor. Well, obviously it is because that
> is what we are trying to do with gum printing when you think about
> it--insolubilize the gum enough so that pigment stays where we want it, but
> not too much so that it stays in the highlights. And this can happen with
> or without exposure, as delineated in the outline.
> Chris
On the advice of my doctor, I've been leaving discussions of this type
unread for the last couple of weeks (the exact advice was that in order
to recover from a serious and stubborn lower respiratory infection, I
must have complete rest and no stress, in addition to the nth round of
antibiotics, and yes I am better now thanks) but this post opened on my
desktop and having seen it, I feel the need to comment.
I did go back and read Chris's post on staining first; haven't we seen
this before, Chris? I think I've probably already commented on some of
the points contained in it. At any rate, I have to say I agree with Judy
here, especially with regard to the rarity of unwanted
"insolubilization" of gum in practice. My observations are consistent
with hers, that while the highlights may fog irreversibly under a very
thin negative, an overexposed print made with a reasonable negative will
almost always clear with longer development. If it doesn't, I would
suspect too much heat as a cause of the "insolubilization", rather than
too much light.
Katharine
This archive was generated by hypermail 2.1.5 : 09/05/03-09:30:46 AM Z CST