In the mid '50's, one of my uncles bought me a monobath kit.
It did, indeed make negatives, which I then contact printed on
P.O.P. paper supplied in the kit. It was easy and fun, ideal
for a ten year old.
In the early '80's, I tried monobath again, mixing a Catechol
developer with Sodium Thiosulfate in it. It did work, and it
produced a printable negative on 620 Verichrome Pan. But the
image was grainy and the film seemed to be between one and
two stops slower than normal. I didn't at that time have
a densitometer, so exactly how much slower is hard to say.
The prints were OK, but the tonality was a bit strange,
rather like the contrast varied inversely with the amount
of local exposure. Supposedly all of these problems can be
addressed in tailoring the developer/fixer to the film
used and adjusting exposure to suit. But it seems an awful
lot of trouble to go to to save about five minutes' fixing.
Oh, by the way, Catechol (orthodihydroxybenzene) is used in
many monobath formulae because its action does not seem to
be affected at all by the presence of Sodium Thiosulfate.
Its developer activity is similar to that of Para-Aminophenol
and Clorhydroquinone, so it is right in the middle range of
developing agents. Another agent which supposedly is not
adversely affected by fixer is Phenidone, but as I have
never tried it in a monobath, I am only repeating what I
I hope this helps you.
Edward M. Lukacs, LRPS
Miami, Florida, USA
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