U of S | Mailing List Archive | alt-photo-process-l | Re: Pinhole gums

Re: Pinhole gums

Hey Katharine,

Thanks-- yes, I suspect that was the problem-- the sizing dried too
quickly, so it was as if the paper had no sizing at all. There was a
faint image, though, but this did react as though I was using an
unsized piece of paper-- though using an unsized piece of Fabriano
works much better for me than this did. Since my exposure times
hadn't changed, I think the cold weather was the issue-- the gelatin
just not having time to sink into the paper. I think I figured as
long as the sizing stayed warm in its little electric pot, that its
temperature wouldn't be affected that much once on paper, but I guess
I was wrong. It's not like it was 30 below or anything-- really only
around 40 degrees-- but enough to make a difference.

On Nov 30, 2008, at 11:19 AM, Katharine Thayer wrote:

I sent this yesterday (Saturday) but it never seems to have been
posted to the list, so I'll try again.

Okay, here's another idea, and understand I'm just grasping at
straws here. Suppose it was so cold and dry that the gelatin
evaporated (or sublimated, even) off the paper while it was drying
in the cold wind. Then since there wasn't really any size on the
paper, you got a heavy pigment stain. You said that it never
develops an image even after developing "forever." This could be a
consequence of severe overexposure, or it could be just heavy
pigment stain. Just thought I'd throw it out there; it's the only
mechanism I can think of that makes sense with the observations, so
far, but as I said, it's rather a stretch and I don't even know if
it makes sense, if this is something that gelatin would logically do.


On Nov 29, 2008, at 1:05 PM, Katharine Thayer wrote:

No, 60 should be fine; most of the time I lived at the beach I was
working at temps in the 50s without ever a problem. But last
winter, I found that 42 (even with a heater going full blast) is
too cold for gum. I'm not sure exactly where the cutoff is, but
somewhere below 50, I think.

Sorry, I'm still skeptical about the gelatin being the cause of
the overexposure. The problems introduced by sizing tend to be
related to coating and to staining; there's no logic or mechanism
I can think of that would explain the gelatin suddenly causing a
great increase in speed of the paper, just because it was cold
where the sizing was drying. I mean, I won't rule out anything
100% when it comes to gum, but that really seems like a stretch to
me. However, nothing else makes sense either. I'll think about
this more,

Hi Katharine,

Yes, that sounds like problems associated with overexposure,
doesn't it? Even though I was inside, the space where I'm
working has only one heating vent, and I have that cut off,
because my flat file sits on top of it. That room is open to
other areas of the house where there is a lot of heat, but that
space is usually colder-- and last week was probably around 60 or
so degrees-- cold for inside, but not so cold that it should have
presented a problem, do you think?. I'm thinking it was a
problem with the gelatine. I was able to coat it with no
problems, though.

On Nov 29, 2008, at 3:21 PM, Katharine Thayer wrote:

Diana, do you have a way of reading the humidity in your
workspace? It sounds, even with the humidifier going, that your
humidity was lower than customary, as evidenced by the problems
with the gum coating setting up too fast. However, there's a
puzzlement here, because as David said, the lower humidity
should mean longer exposure times, but it sounds from your
description that you were experiencing overexposure rather than
underexposure at your usual times. I hate it when things don't
make sense. Another possible variable: I discovered last
winter when working in an unusually cold space that the gum
process doesn't work well below a certain temperature, I'd say
48-50 F. But if you were working inside in a room that's
reasonably temperature-controlled, that should be a problem.

As long as the gelatine didn't set up before it soaked into the
paper (agreeing with David again) I don't think sizing was your
problem here; I think it's something about the environment/
humidity, although it's not behaving as I would expect from my
experience and from industry research related to gum and
humidity. So that's a little baffling.


On Nov 29, 2008, at 11:51 AM, Diana Bloomfield wrote:

Hi David,

Thanks. I didn't think the gelatine was cooling, but possibly
that was happening. The humidity had definitely dropped-- very
dry cold weather. I usually use a humidifier before coating
the gum/pigment/dichromate mix, and I used the same exposure
times as always. So what's happening-- when I coat the paper
(inside), doing everything I've been doing-- the coating seems
to be drying really fast, as I brush-- even though I'm using a
humidifier. I use the same exposure times that have been
successful for me in the past. So when I take out the paper,
after exposure, I can see the faint outline of the image-- but
after soaking it in water, forever, nothing ever happens. If I
brush away the pigment, that helps-- but basically the image
just sits there undeveloped for the most part. So should I be
increasing my exposure time because of the cold, or is my
problem in the sizing? When I was using all this great paper
I'd sized over the summer (when it was hot and humid), I had no
problems, so I'm thinking my problems are at the sizing stage. ?

On Nov 29, 2008, at 2:33 PM, davidhatton@totalise.co.uk wrote:

Hi Diana,

You have to be a little careful that the gelatine doesn't cool
of before it soaks into the paper. Also if the humidity drops
due to the cold, exposure times will probably lengthen. What
problems are you having??

David H

On Nov 29 2008, Diana Bloomfield wrote:

Thanks for posting those, Marek. That is brave of you to post the
originals, too. I like the rich red of those. Almost of my gum
prints have been made with either pinhole, zone plate, or a toy
camera. I made my first couple of gum prints from a lens-based
camera only last week. I couldn't believe how much easier it
was to
register from a sharp, well-defined negative. I had no idea.

I do have a related question maybe you or someone else can
answer I
always size my paper, and dry it, outside, and I sized a batch
week when it was unusually cold here. I had my gelatin and
in one of those electric pots that keeps warm, but I still had to
coat fairly quickly. I've had a lot of gum-printing trouble with
that paper ever since. So is that a known problem-- coating
gum, or
sizing, or hanging it up to dry-- in relatively cold weather? Or
should that not make any difference?

On Nov 29, 2008, at 12:38 PM, Marek Matusz wrote:

> Wow
> It has been so quiet on the list that I decided to post some
> pictures printed over the holidays. They are gum prints made
> pinhole photographs. I have done the worst thing by posting the
> originals as well, but maybe it will create some discussion
> Marek
> http://picasaweb.google.com/marekmatusz1/
> TricolorGumBichromatePinholePhotographs#
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