Re: Help with what I believe is a hardening issue but wasn't

As much as I have learned over the years about the importance of consistency
in time and temperature, I can't believe that the temperature of the sizing
escaped me. I am certain Ms. Mahoney was correct and that the gelatin was
indeed flaking off the paper which resulted in "inadequate sizing". It was
the "case of speckling was created by a student who was developing his
prints in scalding water" quote that really got me to thinking about the
temperature of the gelatin.

Katherine Thayer wrote on Friday, November 12, 2004 1:19 AM

    I agree with Judy and Kate; yes, I think heat is the problem. Having
    never done much sizing, I don't have a lot of experience in this area,
    but I do know that a couple of times when I got the gelatin too hot
    (both times by microwaving it) the sizing failed and made speckles in
    the prints. I'm not sure it matters what happens technically to the
    gelatin; what is important is that overheating the gelatin seems to lead
    to imperfect sizing, for whatever reason.

I couldn't put it better myself!

Ryuji Suzuki wrote on Friday, November 12, 2004 1:43 AM:

    Another trouble of gelatin and heat is that, gelatin solution bubbles
    so badly well below 100C, and when it bubbles, it's very difficult to
    remove them. (Gelatin is a good emulsifying agent, and is often used
    in mass produced hollandaise sauce, for example...) Also, if you add
    dry gelatin flakes into hot water, the gelatin tends to aggregate and
    it's very difficult to mix without leaving gritty texture. I think
    these are bigger reasons why too much heating is warned when gelatin
    is used in recipes.

That is has been my experience and is the reason I have been heating
(apparently overheating) it. So I have spent the past several days working
and reworking my BFK. I was able to salvage my incorrectly sized paper by
recoating it. As for the microwave, it is the only thing I have at the
studio where I work. By hovering over it I am able to control the
temperature fairly well. I have experimenting with different temperatures,
which brings up another question.

It has become obvious to me that the gelatin can indeed be overheated. I am
now wondering if the solution can be underheated. I am not referring to it
being in gel form. It would seem to me that if it were too cool, it could
"clog' the tooth of the paper and cause the gum coating not to adhere as
well. It would be not unlike trying to print on glass or metal. Does this
seem likely? I am going to be trying to find an optimum gelatin
temperature-hot enough to not disturb the tooth-but not so hot to cause the
"sizing to fail". None of my resources, D. Scopick, Keepers of the Light or
D. Demachy, give even a jumping off point. If anyone has any thoughts...

One last question: Does the yellowing when using glyoxal only pertain to
Fabriano Artistico?

In the meantime, thank you all very much for your input. I was able to make
some nice prints this past few days, clean whites and show detail. Yeah!

Candace Spearman

----- Original Message -----
From: "Kate M" <kateb@paradise.net.nz>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Wednesday, November 10, 2004 10:47 PM
Subject: RE: Help with what I believe is a hardening issue

> Gelatine is very sensitive to high temperatures - this will destroy its
> "gelling" ability. I kow this from cooking, not science, so I haven't
> got a clue why - think it destroys the protein chains (?). So heating up
> your gelatine until its really hot is NOT good! It's probably shrinking
> up while drying and flaking off the paper, causing the speckles. I use a
> water bath of about 50deg C to reliquefy. I also keep unused gelatine
> solution in the fridge. You will know if it is really off - it smells
> like a dead animal! I use formaldehyde to harden by adding it to the 2nd
> gelatine coat. I get it through my University laboratory - they always
> have it.
>
> Hope this is of some use
> Kate
>
> -----Original Message-----
> From: ericawd [mailto:ericawd@memworld.com]
> Sent: Thursday, 11 November 2004 1:37 p.m.
> To: alt-photo-process-l@sask.usask.ca
> Subject: Re: Help with what I believe is a hardening issue
>
>
> I will admit I may have been a bit lackadaisical at times with the
> gelatin. With the last batch I may have let it set out a good while
> after initially adding it t the cool water for heating it for the first
> coat. So far on the new BFK I have done only the shrinking step and
> plan to complete the sizing process tomorrow. I want to try and avoid
> whatever
> mistake(s) I made on the last batch. To that end I have a few more
> questions.
>
> In answer to the suggestions below, I am sure the gelatin was the
> correct formula-four .25 ounce packet of gelatin to a liter of water.
> The speckling is very much in the non-image areas. Also, I always
> develop the prints in water at 75-77 degrees which I arbitrarily picked
> because that is what the ground water runs here in Memphis during the
> summer months. The most likely suggestion is the spoilage issue.
>
> The first question: Is it possible to get the gelatin too hot when
> sizing? I heat it in a microwave to the point that I am unable to put my
> finger in for more than a second. There is usually steam coming off the
> surface. Could this be related to my speckling problem and related to
> developing prints in scalding water?
>
>
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Received on Sun Nov 14 18:39:25 2004