[pure-silver] Re: Microphen and possible formulas
- From: Ryuji Suzuki <rs@xxxxxxxxxxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx, dickburk@xxxxxxxxxxxxx
- Date: Sat, 12 Feb 2005 07:09:15 -0500 (EST)
From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
Subject: [pure-silver] Re: Microphen and possible formulas
Date: Sat, 12 Feb 2005 02:54:28 -0800
> Hydroquinone is peculiar in D-76. If the Metol is left out
> very little development takes place. If the Hydroquinone is
> left development is nearly as full as with it. Evidently,
> the regenerative action of Hydroquinone is not affected in
> the same way by pH is activity. Carlton and Crabtree tried
> both combinations and show the density resulting by both
> combinations. Where the Metol was left out the density was
> just detectable.
I don't understand what you are trying to say. In D-76 hydroquinone
regenerates Metol. Without hydroquinone, D-76 cannot be reused as many
times; even with some compensation in processing time, the loss of
speed and density will be noticeable. In ID-68 type developer, if you
leave out hydroquinone, you'll only get very low density image.
> The MSDS for Microphen shows two ingredients not in the
> ID-68 formula. One is Sodium Tripolyphosphate, which I
> believe is a sequestering agent, the other is Potassium
> Metabilsufite.
> I wonder if the Metabilulfite is for the purposes of
> adjusting the pH in compensation for the Tripolyphosphate.
Microphen comes in two packages. If I remember correctly, part A
contains developing agents and acids, including metabisulfite. Part B
contains sulfite and alkaline agent. They probably didn't want to make
one part package for some reason, and also didn't want to leave
developing agents without sulfite. Just a guess, though.
> Ryuji's suggestion about trying both and comparing results seems a
> lot simpler procedure.
I didn't say that. I simply said it's probably better to forget about
guessing the formulae of proprietary products. For one thing you'll
never know what they are for sure. And for another, there is no reason
to mix your own version of a developer today and buy packaged version
tomorrow.
--
Ryuji Suzuki
"Keep a good head and always carry a light camera."
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