[alt-photo] Re: casein history
zphoto at montana.net
Fri Jul 20 00:28:52 GMT 2012
Glad you are trying this! Gelatin was susceptible to melting in hot water or weather and casein would help with that, esp. in summer months. Here is part of the patent description that may be of some help.
My third improvement consists in replacing the gelatine and its analogues in the above compounds wholly or in part by certain other organic compounds having the property of insolubility in warm water but of solubility in some other chemical agent, such as ammonia or the alkalies or salts; and the best substances I am at present acquainted with are the proteine compounds which possess the specified properties, such as caseine, legumine, modified albumen, and their congeners. A pigment compound so formed, and mixed with a bichromate, is sensitive to light; but the picture is not revealed or developed by hot water until a few drops of ammonia or other alkali possessing the like property has been added to the water. In carrying out this part of my invention I form a curd of skimmed milk, as in making cheese, by precipitating the caseine with rennet or by an acid. I collect the curd on a filter, and, after partially drying it by pressure, I dissolve the caseine or curd in dilute liquor ammonia. This solution—which should be as thick as the previously described solution of gelatine in four and a half parts of water—I use instead of a portion of the gelatine solution; that is to say, I take away part of the gelatine solution and substitute in lieu thereof an equal portion of the caseine solution. The quantity so substituted may be greatly varied. Ten per cent of the caseine solution so substituted renders the resulting compound insoluble in water until a certain quantity of ammonia has been added, and twice or three times that quantity does not prevent a workable tissue compound being formed; and in making such a pigment compound I find it best to mix the caseine solution with that of the soap, and add the two together to the gelatine. Soap, however, is not absolutely necessary, as the caseine itself gives flexibility to the tissue, and thus supersedes the necessity of employing the soap...
Christina Z. Anderson
On Jul 19, 2012, at 11:30 AM, Evan J Hughes wrote:
> 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,
>> 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.
>> Christina Z. Anderson
> Alt-photo-process-list | http://altphotolist.org/listinfo
More information about the Alt-photo-process-list