"Keith Tapscott."
wrote in message
...

Richard Knoppow;822714 Wrote:
"Keith Tapscott."
wrote in message
...-

Has anyone tried this developer?

http://tinyurl.com/kqegre




--
Keith Tapscott.-

I have not tried it.
I did a little searching around. The box suggests its
D-76d, which is the buffered form of D-76. Kodak's
packaged
D-76 is of this type. The buffered formula was devised in
1929, a couple of years after the release of the original
D-76 formula, because it was found that the original
slowly
increased in activity causing a significant increase in
the
contrast obtained after a given developing time. Kodak
labs
found that the pH of the solution increased slowly with
time
and that using a borax-boric acid buffer system would
control it. There is an MSDS for the Foma product at the
Freestyle site but its wrong listing sodium thiosulfate
(hypo) as one of the ingredients. Of course, they mean
sodium sulfite. The only other ingredients listed are
metol
and hydroquinone so its incomplete in any case.


Kodak D-76 (original 1927 formula)
Water (at about 125F or 52C) 750.0 ml
Metol 2.0 grams
Sodium Sulfite, desiccated 100.0 grams
Hydroquinone 5.0 grams
Borax, granular 2.0 grams
Water to make 1.0 liter

Dissolve chemicals in order given.

Kodak D-76d (1929 buffered formula)
Water (at about 125F or 52C) 750.0 ml
Metol 2.0 grams
Sodium Sulfite, desiccated 100.0 grams
Hydroquinone 5.0 grams
Borax, granular 8.0 grams
Boric acid, crystalline 8.0 grams
Water to make 1.0 liter

Do not use powdered Boric acid, it dissolves only with
difficulty.
Mix chemicals in order given.

The two formulas have about the same activity when
freshly mixed but the buffered version is stable where
the
original is not.



--
Richard Knoppow
Los Angeles, CA, USA


Richard, you say that: "The two formulas have about the
same activity
when freshly mixed but the buffered version is stable
where the
original is not."

I have been researching D-76 (ID-11) and it`s derivatives
for quite a
few years now, including mixing some of the formulas from
scratch. I
have to say that I disagree that D-76 and D-76d have the
same activity
and that the buffered-borax version needs significantly
longer
development times to match the film contrast of those
films which were
developed in the commercial formula.
I also found that the standard formula seems to match the
commercial
D-76 developer for developing times, unlike D-76d.
Ryuji Suzuki provided some useful data about D-76 and it`s
variants on
his website. The MSDS for D-76 list diboron trioxide/B2O3
(boric
anhydride), but from correspondence with a former employee
at Kodak, is
that D-76 commercial is identical to the published
product, although
there is a special method for encapsulating the
developing agents, so
they are protected against the other constituents in the
single-powder.
There are patents for packaging single-powder developers
which you may
be of interest to you.
It wasn`t until recently that I noticed the Foma Fomadon-P
packaging
that gave me a clue as to why the development times are
radically
different.
Take a look at the MASSIVE DEVELOPMENT CHART on the
Digital Truth
website for Fomadon-P.




--
Keith Tapscott.

Kodak published a long technical paper in 1929 (I'll
get the citation if you want) detailing the research on
D-76. D-76 was originally published in a brochure describing
a new fine-grain film for duplicating motion picture
negatives, I have never been able to obtain a copy. It was
rapidly adopted as the standard motion picture negative
developer for the industry. It was originally used in
rack-and-tank developing machines.
It was discovered that there were problems with
obtaining consistent development time. This was eventually
traced to a slow rise in pH. Kodak cured this by using the
buffer but the real cause was not discovered for a couple of
decades. It turns out that a slow reaction between the
hydroquinone and the sulfite generates a small amount of
sodium hydroxide, enough so that after a month of storage
the developer will produce the same gamma as fresh developer
in slightly more than half the time. With the buffer the
development time remains constant. The paper shows that the
activity of the two formulae is very similar when fresh.
Note that the activity of the buffered solution can be
varied over a quite wide range by adjustment of the buffer.
The paper includes a chart showing the variation with the
ratio of the two components. This was an advantage where it
was difficult to adjust processing speed, hense time, in
automatic or semi-automatic machines.
There are alternate names for a lot of common chemicals
plus they can become different when in solution than when
dry. Its possible that the current packaged version of D-76
is not exactly identical with the published D-76d but it is
the same stuff. I can't account for large variations in
activity other than the effects of poor control in the
experiments. BTW, if you read Ryuji's stuff you know that
measuring pH of photographic solutions, particularly
developers, is not trivial. I think Kodak's old research is
still valid.
I am aware of Ryuji's work on developers. He found, for
instance, that the optimum amount of sulfite for a D-76 type
developer is around 80 grams/liter. The difference between
that and the 100 grams/liter in D-76 is not large but is
measurable. Agfa, in their Agfa 17, uses 80 grams/liter plus
a slightly different ratio of hydroquinone to metol. They
also add 0.5 gram/liter of potassium bromide. Kodak found
that a small amount of bromide added to the unused developer
would actually increase effective film speed slightly by
suppressing a small amount of fog characteristic of D-76. If
the developer is re-used the bromide leached out of the
emulsion has the same effect. In replenished systems adding
some bromide at the start is similar to the "ripening" or
starting solutions used in color developing machines.
Kodak also found that the presense of hydroquinone had
very little effect on development. The pH of D-76 is too low
to activate hydroquinone so it acts as a regenerator for the
metol extending the capacity of the developer. In fact, D-76
without the hydroquinone is an effective developer and its
life can be extended by using more Metol, perhaps 5
grams/liter as in D-23.
Before D-76 was devised the motion picture industry used
a variety of developers including Pyro with development by
inspection. One reason for the supplanting of this by a
different developer was that with the coming of sound
pictures the film used for picture negative changed from
orthochromatic to panchromatic eliminating development by
inspection plus, at least for sound on film, a much tighter
control of gamma was necessary. This required controlled
automatic machines for release printing which, in turn,
required much tighter control of the negatives since the
prints could not be individually taylored to the negatives
without changing the sound characteristics.




--
Richard Knoppow
Los Angeles
WB6KBL