DShack (TSHACK@SILVER-BAYOU.COM)
Sat, 03 Jul 1999 16:05:10 -0700
I was just out cruising used bookstores trying to find some of these
antiquated reference texts that some of you quote from, and that I covet.
I happened across one book called "Henley's Formulas for Home and Workshop"
originally published in 1907 and 1927. This is a reproduction copy I have.
Though it has an extensive section on photography, in another section it had
something called "photography without light", or catatype. I'll quote what
it says:
"It is a well-known fact that the reactions of the compounds of silver,
platinum, and chromium in photographic processes are generally voluntary
ones and that the light really acts only as an accelerator, that is to say
the chemical properties of the preparations also change in the dark, though
a longer time is required. When these preparations are exposed to light
under a nagetive, the modification of their chemical properties is
accelerated in such a way that, through the gradations of the tone-values in
the negative, the positive print is formed. Now it has been found that we
also have such accelerators in material substanfces that cfan ber used in
tghe light,k the process being termed catalysis. It is remarkable that
these substancfes, called catalyzers, apparently do not take part in the
process, but bring about merely by their presence, dedomposition or
combination of other bodies during or upon contact. Hence, catalysis may be
defined, in short, as the act of changing or accelerating the speed of the
chemical reaction by means of agents which appear to remain stable.
Professor Ostwald and Dr. O. Gros of the Leipsic University, have given tghe
name of 'catatypy' to the new copying process. The use of light is entirely
done away with, except that for the sake of convenience the manipulations
are executed in the lifht. All that is necessary is to bring paper and
negative into contact, no matter whether in the light or in the dark. Hence
the negative (if necessary a positive may also be employed) need not even be
transparent, for the ascending and descending action is produced only by the
quantity in the varying density of the silver powder contained in the
negative. Hence, no photographic (light) picture, but a catatypic picture
(produced by contact) is created, but the final result is the same.
Catatypy is carried out as follows: Pour dioxide of hydrogen over the
negative which can be done without any damage to the latter, a lay a piece
of paper (sized or unsized, rough or smooth, accfording to the effect
desired); by a contact lasting a few seconds, the paper receives the
picture, dioxide of hydrogen being destroyed. From a single application
several prints cfan be made. The acquired picture - still invisible - may
now in the further course of the process, have a reducing or oxydizing
action. As picture-producing bodies, the large group of iron salts are
avbove eminently adapted, but other substances, such as chromium, manganese,
etc, as well as pigments with glue solutions may also be employed. the
development takes place as follows:
When the paper whidch has been in contact with the negative is drawn through
a solution of ferrous oxide, the protoxide is transformed into oxide, hence
a yellow positive picture results, which can be readily changed into other
compounds, so that the most varying tones of color can be obtained. With
the use of pigments, in conjunction with a glue solution, the action is as
follows: In the places where the picture is, the layer iwth the pigments
becomes insoluble and all other dye stuffs can be washed off with water.
The chemical inks and reductions, as well as color pigments, of which the
picture exists, have been carefully tested and are composed of such as are
known to possess unlimited durability.
After a short contact, simply immerse the picutre in the respective
solution, wash out, and a permanent picture is obtained."
The is the entire text under the catatypy category. This is very intriguing
to me. Does anyone know anything about this?
Dwight
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