[pure-silver] Re: D-76 and variations
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Tue, 29 Nov 2005 12:14:05 -0800
----- Original Message -----
From: "Nick Zentena" <zentena@xxxxxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Tuesday, November 29, 2005 11:37 AM
Subject: [pure-silver] Re: D-76 and variations
On Tuesday 29 November 2005 14:15, Koch, Gerald wrote:
still see this chesnut spouted as gospel on the web.
Strictly speaking
only D-76 is D-76 but I am willing to consider all
developers that are
similar even D-76H.
But packaged Kodak D-76 isn't D-76 is it?
Nick
It is. Its approximately the same as the buffered version
in the paper by Carlton and Crabtree of Kodak Labs published
in 1929. D-76 was originally formulated by John Capstaff, of
Kodak Labs and announced in a booklet (1926) describing a
new film for duplicating motion picture negatives. It became
popular for processing the negatives themselves. It was one
of the first developers to be formulated on the basis of any
scientific knowledge of chemistry.
Evidently, the rise in activity became evident quickly.
Consistency is important in motion picture processing
because negatives made at different times must be intercut.
Carlton and Crabtree undertook an extensive investigation of
D-76. In the paper they report on something like 30
variations. The one which is recommended is D-76 with the
inclusion of a buffer system. Kodak called this formula
D-76d. As a matter of interest there was also a D-76c but
that was devised later for low contrast development of
scientific plates. D-76, D-76d, D-76c, and DK-76, the Kodalk
version, are AFAIK the only D-76 developers devised by
Kodak. Plenty of other M-H Borax developers were devised by
others. Most of these were for use in automatic developing
machines for motion pictures. Kodak's current developer for
this purpose is D-96 which is similar to D-76 but with
different ratios of developing agents. It might be of some
interest.
Kodak D-96
Water (125F or 52C) 750.0 ml
Metol 1.5 grams
Sodium sulfite, dessicated 75.0 grams
Hydroquinone 1.5 grams
Potassium bromide 0.4 grams
Borax, granulated (decahydrated) 4.5 grams
Water to make 1.0 liter
Recommendation for current Plus-X motion picture stock (not
the same film as Plus-X still film) is 5 minutes at 70F in a
continuous machine for a gamma of 0.65 to 0.70
The paper I keep refering to is:
"Some Properties of Fine-Grain Developers for Motion Picture
Film", H.C.Carlton and J.I.Crabtree
_Transactions of the Society of Motion Picture Engineers_
Vol XIII, No.38, 1929 (p.406)
See also:
"Borax Developer Characteristics", H.W.Moyse and D.R.White,
(DuPont Labs) loc.cit. p.445
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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