U of S | Mailing List Archive | alt-photo-process-l | Re: Gum & the commercial ?

Re: Gum & the commercial ?

On 11/3/06 11:43 PM, "Christina Z. Anderson" <zphoto@montana.net> wrote:

> Halvor said:
>>> (possibly chloral hydrate or acetic acid to allow cold dev of gelatin)
>> I had forgotten about pH influence on "solubility" of gelatine, this calls
>> for a few more days in the lab :-)
>> Is there any best article or well referenced starting point for this
>> subject? (overview & history of the praxis of "gum printing") -
> Yes--the British Journal of Photography from 1850's on--I'm now up to 1930
> this week (it wasn't called the BJP in the beginning).

Was afraid of that answer :-) The whole collection is in the library, but
have a feeling if I first sit down to read that I wont leave in a year or
so... Or wont get anything done..

> But the chloral 
> hydrate and glacial acetic acid were Herr Watzek's formula in the Weiner
> Photographische Blatter (whatever that might be). It is gelatine 40 grains,
> chloral hydrate 25 grains water 100 minims.
> What the heck is chloral hydrate anyway??? Ohhhh, for a chemistry degree....

Apparently chloral hydrate is an antidepressant or hypnotic drug, may be
something a gum printer would keep around :D ... But if I should make one
guess here it sounds like Hydrochloric acid or HCl which would do something
very similar as acetic acid in this connection, in my experience... Others
may know.

> I unfortunately don't read German; I have had several German books
> translated for me but there are many more on gum that you can get all this
> more techie stuff out of.  Go into WorldCat or some library world catalog
> and google gum bichromate or gummidruck and German if you are so lucky to
> read it. They were prolific around the 1900's with gum books.

Unfortunately I was given the choice between learning German or hunting in
school... Pretty idiotic... Can however guess my way through it.. Will look.

>> I have had a somehow simplified view that gum printing is gum arabic
>> punctum, but obviously the physical method seems more important, or
>> defining,  than the materials. Despite the variety of names or
>> terminology.
>> I recognise some of what have been mentioned here, but that is all from
>> various introductions for different subjects.
>>> These commercial "gum" papers must have been intended to use as single
>> layered then (?).. (Interesting, either better recipes or different ideas
>> of
>> "image quality").
>> Halvor
> Halvor, I just shared the different ingredients in gum throughout history
> for interest--but it seems that no one uses the extra ingredients
> anymore....  Some may still have possibilities nowadays though--I was going
> to test one or two. But it seems that they were all vying for trying to
> duplicate Artigue paper, or guess its secret formula.  Yes, it was a one
> coat paper, as were all the gum papers, so with tricolor or multiple
> exposures some of the other ingredients became either overkill or disproved
> as the "latest greatest thing".
> Chris 

More later :-)