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Old February 24th 14, 08:02 AM posted to rec.photo.darkroom
Richard Knoppow
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Posts: 751
Default Film almost transparent


"Jean-David Beyer" wrote in message
...
On 02/23/2014 11:54 AM, Richard Knoppow wrote:

"Franssoa" wrote in message
...
Hello,

=

I do not remember who said it (Kenneth Mees?) that the
plethora of film
developing formulae gives us many means by which identical
results may
be obtained. Start with D-76d or something and change only
if you need to.


Attributed to Kenneth Meese but I don't remember where I
first saw it. I must agree, Kodak did a lot of research on
reliable developers, their characteristis are well
established. Almost every manufacturer of film, paper,
chemicals, had some version of the Kodak formulae. The main
differences were in AGFA formulas which sometimes specified
potassium salts in place of sodium. The main reason was that
AGFA produced enormous amounts of potassium as a by-product
of their chemical industry. They also had a couple of
patented reducing agents (like Rodinal). For the most part,
until the relatively recent evolution of ascorbic acid and
Phenidone derivatives, most formulas used Metol (originally
an AGFA trade-name, called Elon by Kodak) and hydroquinone
in various ratios depending on the results desired. While
some very modern formulas, like Xtol, are somewhat superior
to the old ones its not be a lot so one can do very
satisfactory work with D-76 (preferably in its buffered form
published by Kodak as D-76d) for film and D-72 (formula
version of Dektol) for paper. I am fascinated by the use of
eccentric developing agents like tea or coffee. They may
have properties as reducers but are thoroughly inferior to
the half-dozen agents that were found over the last century
and a half. Even the use of pyro is somewhat eccentric
because M-H formulas are more reliable and generally longer
lasting. Its fun to experiment but for serious work an
established and reliable developer is very desirable. There
are not many left in packaged form. I am not sure what
Kodak is currently offering but I think T-Max RS, which is
an active developer which is its own replenisher, Xtol,
which yeilds somewhat finer grain than T-Max and similar
developers from Ilford. Ilford also offers Perceptol, an
extra-fine-grain developer identical to Kodak Microdol-X
which is now discontinued.


--
Richard Knoppow
Los Angeles
WB6KBL