[Leica] Pyro/Vitamin C developers

["Jonathan Borden" <jborden@mediaone.net>]

Tom,

...>  The Catechol looks virtually like the PMK on the older, thicker
emulsions
> but with less distinct stain, sharpness is similar and shadows are a bit
more
> blocked than the PMK. On TMY the Catechol does not work very well, way too
> thin and severely blocked shadows. Probably need to rate the film at
around
> 160 to even get printable negs.  My Catechol is rather old and could have
> lost some of its "punch" in storage.
>  The idea of adding Vitamin C to Pyrocatechin is interesting. I have used
the
> E-76 formula and I found it very much like D-76, but the Vitamin C to
> Pyrocatechin is intriguing. Have you got any idea of quantities and
starting
> times for that mix?
>  I probably should get my old densitometer working again, but I hate
plotting
> curves and then it starts to become more like a job - at least now I can
just
> play with chemistry and enjoy it.
> Tom A
>

    The subject of Vitamin C developers is indeed interesting, popularized
by Kodak's Xtol and again by the "Rollo pyro" soup described initially by H.
Leban and now sold by Bostick & Sullivan (Vitamin C modified PMK).

    I've heard that TMY doesn't take to any of the staining developers well
and haven't tried it.

    Here is a formula used for holography:
PART A sol
        (Pyro)Catechol 10 grams
        L-Ascorbic Acid (Vitamin C) 5 grams
        Sodium Sulfite (anhydrous) 5 grams
        Urea 30 grams

PART B sol
        Sodium Carbonate 30 grams

Mix each into 500 ml. warmed distilled water. Part A is good for one month,
Part B indefinitely. Add equal parts A & B to activate just a minute or two
before use, just enough to cover one hologram. Mixed solution is active for
20 minutes. Discard after one use to assure each hologram has optimum
development. Develop for at least TWO minutes @ 68 degrees F. Adjust...

Jon