From: Richard Knoppow (dickburk@ix.netcom.com)
Date: 05/27/01-03:27:50 PM Z
At 05:03 PM 05/27/2001 -0400, you wrote:
>
>
>On Sun, 27 May 2001, Mare-Verde wrote:
>> ...As for Dektol also having metol, that may well be
>> the case but my experience is that often more interesting results come from
>> other developers although I'm unsure if this is because they have more
metol
>> or not. I'm just going on some of the things Robert Asman has mentioned.
>
>Hi Michael,
>
>Kodak has always been very coy about publishing the formula for Dektol, as
>if the average photographer would mix his/her own when they can buy it
>ready mixed for $5/gallon. However, they say it's "similar" to D-72, which
>does have metol (& I have seen "Dektol" given simply as D-72). Maybe the
>other formulas have something else.
>
>
In reference to this only. Kodak's packaged chemistry is proprietary. One
can usually get a good idea of its formulacions from the MSDS, although
these may not tell the whole story. For Kodak these are available from the
Kodak web site and from the Siri site at the University of Vermont.
The difference between D-72 and Dektol is probably the inclusion of a
sequestering agent or agents and generaly in powdered chemicals, in the
choice of compounds which are most stable in dry form but come out the
same when dissolved.
If you look at the formula for D-72 you will find that the chemicals are
given in the order in which they must be dissolved. The important one is
the Metol/Elon (different brand names for the same thing). Metol will not
dissolve in sulfite so it must go in first. However, Kodak has done
something to allow mixing all the ingredients of Dektol in one powder. I
suspect this is done by adding a seqestering agent which is in too small a
quantity to require showing it on the MSDS, but they might be doing
something else. The same for D-76 and some other packaged Kodak developers.
Dektol has been around for a very long time and is nearly a generic
high-activity developer. It works well for re-development after bleaching
operations since it acts quickly and has relatively little sulfite, so it
has little tendency to dissolve the halides produced by the bleaching.
Virtually all of the paper manufacturers made something like Dektol / D-72,
the differences being small variations in the amounts of the ingredients.
Dektol is available as a liquid concentrate in the US under the name
Polymax T. I think in Europe/UK its still sold as liquid Dektol.
Ilford Bromophen is a similar to Dektol but uses Phenidone instead of
Metol. The published formula is ID-62. Its performance is nearly identical
to Dektol although it may yield colder tones on some papers. It has the
advantage of being usable by people who have a Metol sensitivity.
Another good developer for redevelopment after bleaching is any Amidol
print developer.
---- Richard Knoppow Los Angeles,Ca. dickburk@ix.netcom.com
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