Richard Knoppow (dickburk@ix.netcom.com)
Wed, 19 May 1999 18:57:59 -0700
At 06:47 PM 5/19/99 +0000, you wrote:
>Greetings-
>
>Richard K. requested the formula for the GP-2 gold toning formula: (as I
>said earlier, this comes from Douglas Nishimura at RIT)-
>
>water 750ml
>gold chloride 1% [A] 0.5g
>tartaric acid 1.0g
>thiourea [B] 5.0g
>sodium sulfate (desicated) 15.0g
>water to make 1.0 liter
>
>Please note that this formula seemed to be used with microfilms: the source
>for the development of this formula was listed as: Henn, R.W., and D.G.
>Wiest. "Microscopic Spots in Processed Microfilm: Their Nature and
>Prevention." <Photographic Science and Engineering>, Volume 7, number 9,
>September-October 1963. Society of Photographic Scientists and Engineers,
>Inc. pp 253-261.
>
>And also Henn and Weist."Properties of Gold-Treated Microfilm Images" (same
>journal as above) Vol. 10, No. 1, January-February 1966, pp 15-22.
>
>The information sent to me is a total of five pages with *lots* of esoteric
>sounding notations about the formula and its use....
>
>
Thank you so much for posting this. I think this must be part of the same
research project that led T.H.James to discover that a small amount of hypo
left in an emulsion would protect the image silver. I will have to get the
paper. I would be interesting to know the relativly effectiveness of GP-1
and GP-2 and GP-2 vs: selenium. According to James GP-1 was not as
effective as Selenium and neither alone was as good as the combination of
either with the small hypo residual.
AGFA Sistan probably fits in here also, its a weak solution of postassium
thiocyanate, somewhat along the lines of the stabilizer used in the
stabilization process. All these apply to negatives as well as prints.
They are more important wiht microfilm than with ordinary film because of
the very fine grain which makes them much more suseptible to the
depradations of various chemicals in the atmosphere, as are the very fine
grains of silver printing paper emulsion.
----
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
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