Re: A D-76 Recipe from Developing by CI Jacobson

----- Original Message -----
From: "Michael Healy" <emjayhealy@earthlink.net>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Friday, November 26, 2004 1:49 PM
Subject: Re: A D-76 Recipe from Developing by CI Jacobson

> It's curious that this is the same formula as published in
> Anchell & Troop, except that
> theirs calls for only 2g's of metol rather than Jackson's
> 5g's. I wonder what happens
> from doubling the metol and leaving all else unchanged?
> Will it just develop more
> aggressively? Act more solvently on thegrains? Was
> Jackson's formulated for higher
> dilutions maybe?
>
> Mike
>
>
   The Jacobson formula, if quoted correctly is a misprint.
The original D-76 formula is:

Water (125F or 52C) 750.0 ml
Metol 2.0 grams
Sodium Sulfite, dessicated 100.0 grams
Hydroquinone 5.0 grams
Borax, crystaline 2.0 grams
Water to make 1.0 liter

This formula was devised by John G. Capstaff, of Kodak
Research Laboratories, and introduced in a 1926 Kodak
publication on the application of a new duplicating film for
motion picture negatives. It was soon adopted as a standard
fine-grain developer for motion picture negative film.
Before long it was discovered that while stored the activity
of this developer increased slowly. The exact reason for the
increase was not discovered for decades but it was known
that a reaction in the solution resulted in a slow rise of
pH causing the increased activity. Considerable research was
carried out by the labs to find a cure for this and to
generally explore the nature of the developer. In 1929 a
paper was published by Carlton and Crabtree of the labs
discussing the findings of the research. About 30 variations
of the D-76 formula are described in the paper. The one of
principle importance is the buffered version I copied to
this list a day or so ago. This formula replaces the 2 grams
of Borax per liter of the original formula with a buffer
consisting of 8 grams of Borax and 8 grams of Boric acid per
liter. This formula has stable activity and pH. A comparison
published in the paper shows that the original formula
increases activity enough so taht after two months of
storage without use, the development time for a givn
contrast (gamma) falls to a little more than half the time
required by the fresh solution. The buffered solution has
constant development time, within experimental error,
throughout this period.
   The Kodalk version of D-76, which is shown in some Kodak
publications as DK-76, was at first throught to offer better
buffering than Borax. However, it is no more stable than the
Borax form and much less stable than the buffered form.
   D-76 remains an excellent developer to this day and also
remains the standard of comparison for other developers.
   I get an occasional advertising blog from Fine Arts Photo
Supply. In the last one was a criticism of D-76 saying it
was old-fashioned technology, that it produced chalk like
highlights and other stuff. This is plain nonsence. D-76
works as well as any current developer although some newer
ones give slightly better grain and speed (Xtol for
example). However, tonal rendition is not so much a function
of the developer as it is of the film and of technique.
Anyone getting "chalk like highlights" has a problem with
their darkroom practice that a change in developer is not
likely to cure.
   I don't know what effect the addition of Metol to the
formula would have. Not very much I suspect since the
activity is not controlled by the amount of the developing
agent as much as the pH. In the case of D-76 the
Hydroquinone is inactive as a developer (it will develop
just fine without it) but does have a function in extending
the life of the developer by regenerating the Metol.
   BTW, D-76 and several variations of it remained the
standard developer for motion picture negatives all during
the black and white period.

---
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix.netcom.com