From: Jarred J. McCaffrey (jmccaffr@cs.uml.edu)
Date: 05/29/00-01:27:59 AM Z
I would like to experiment with some very large (handmade) negatives in
homebrewed cameras. Carbon has been touted in more than one book as being
a faster printing emulsion than silver based processes. E.J. Wall wrote
of a formula for carbon transfer which only required 1/4 second exposure.
Is it the experience of list members that carbon gelatin emulsions are
potentially faster than handmade (not commercial) silver based emulsions?
Is there a faster process that might better suit the handmade film
purpose? Whether or not carbon is the ideal choice, I would greatly
appreciate postings of fast carbon emulsion formulas from your experience
or advice on creating a fast carbon emulsion.
As a starter here are two fast carbon emulsions from E.J. Wall's _The
History of Three-Color Photography_. I have quoted the text exactly.
(p 692)
W. Wadhams, A. Ziehm, H. A. Sonderman and P. Woithe patented a
modification of the dichromate sensitizer, which is stated to give great
speed in printing. One formula is:
Potassium dichromate 30 g.
Magnesium chloride 10 g.
Sodium acid phosphate 5 g.
Water 1000 ccs.
Gelatinized surfaces should be immersed in this for about 2
minutes at a temperature not exceeding 18 degrees C. and dried. The
exposure is stated to be reduced to about 1 second under an ordinary
negative. An alternate solution is:
Anilin hydrochloride 2 g.
Sodium acid phosphate 5 g.
Magnesium chloride 10 g.
Water 1000 ccs.
Dissolve and add:
Potassium dichromate 30 g.
This is to be used as the former and allows a print to be obtained
in one-fourth second. The exposed surface should be treated with hot
water at 45 degrees C., to which ammonia or borax may be added. The
colorless reliefs thus obtained may be stained up.
end quote
As an aside, I have no idea what anilin hydrochloride is and cannot find
any reference to it on the internet at all. Any information there would
be appreciated as well.
Thank you very much!
Jarred McCaffrey
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