[alt-photo] Re: casein history

[Evan J Hughes]

Hi Chris,

    I hope to have another go at adding casein to carbon tissue over the 
next few weeks, but on thinking about the behaviour of casein, do you 
know what the advantage of adding casein to carbon tissue was thought to 
be?

    My first thought was that it may make the tissue more sensitive and 
therefore expose faster, but otherwise, many of the properties of casein 
are not necessarily an advantage, i.e. it is important to have a recipe 
that develops easily in warm rather than hot water to reduce issues with 
bubbling; the unexposed tissue needs to melt very easily to allow the 
support paper to be stripped away.   I do not see how the casein may 
help with adhesion during transfer, although it can make a very 
effective glue.

   I plan to try a few glop mixes ranging over 10% to 30% of casein; 
have you noticed how much pigment was used in the gelatine-casein carbon 
tissues?   I wonder if the pigment quantity may be very high so that a 
very thin, high contrast tissue can be poured; rapid automated 
manufacture is then much more simple which would be important for 
mass-produced tissue.

      Best regards,

            Evan

> Date: Wed, 18 Jul 2012 17:07:58 -0400
> From: Christina Anderson<zphoto at montana.net>
> To: The alternative photographic processes mailing list
> 	<alt-photo-process-list at lists.altphotolist.org>
> Subject: [alt-photo] Re: casein history
> Message-ID:<60FD5C48-353D-401A-838F-0386DC29C81E at montana.net>
> Content-Type: text/plain; charset=windows-1252
>
> Marek, Ian, Phillipe, and others,
>
> I have no "in" with the Fresson family to know if casein is part of the composition. I have numerous articles on the composition of Fresson paper, but none say they know it for a fact, all say they are guessing it. Thus a definitive answer can only be had from electron microscopy.
>
> I know of two that have done that and nothing about casein has been mentioned, supporting Phillipe and Ian. However, in talking with a conservator, casein would be a hard substance to spot because of its various components.
>
> Here is the actual answer from the conservator:
>
> "The identification of casein is not a trivial matter. It is a protein so its FTIR signature is very close to both gelatin and albumin. There is a chance to use the XRF (the elemental analysis) when looking for phosphorus but that is also complicated due a limited sensitivity of the XRF for light elements (like P etc.)?.."
>
> The reason I brought up the initial issue, and Marek responded to it, was that casein was proposed in an original patent of carbon tissue in combination with gelatin. This was 1870, long before Artigue, Fresson, and Leto papers, direct carbon tissues. I could go on and on about this historical milieu but suffice it to say that it is a question to pose, or outrule, at the very least, and I think a definitive "no" is somewhat premature, given the secrecy of the formulas involved.
>
> My GUESS is a "no" along with Ian and Philippe, but that is not supported by evidence YET. The much more intriguing question is how much early carbon transfer tissue contained casein and is it a viable option today? Or did problems present themselves with casein in its early use that made the Autotype company abandon its use after 1870? There are hints at casein's problems in the literature, at any rate.
>
> Chris
>
>
> Christina Z. Anderson
> christinaZanderson.com
>


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