Tony's Pyro info

[Tom Deering <tdeering@xxxxxxxxxxxx>]

Tony said:
>The attachment is a Word doc. file, so if you have Microsoft word,
>or almost any text program it should run.

I have translated Tony's DOC file into plain text below.  This makes it
readable by people who don't use Word, and makes it many times smaller.

-----

PYRO
The following is copied from the Ilford Book of Photography 1954. I hope it
is of some use to you.

PYRO.(Pyrogallic Acid, tri-hydroxy-benzene)

This is generally sold as very bulky light feathery crystals, one ounce of
which will fill a 10 ounce bottle. Pyro, which is extremely poisonous, is
very soluble in water; the solution rapidly turning brown on contact with
air and becoming muddy after some time due to the formation of an insoluble
compound. If the solution is alkaline, this change takes place in a few
minutes. Hence, Pyro developers are compounded with a large quantity of
preservative. Even so, they tend to give an image in which a certain amount
of brownish stain is combined with the silver. Solution that has become
discoloured likewise stains the entire coating of gelatine on a negative.
Never the less, Pyro developers are unsurpassed for bringing out the
maximum detail in shadows without blocking up the highlights.

Page 196.
Pyro-Metol developer.
This developer, in the absence of sulphite gives a very yellow image and is
invaluable in cases of great under-exposure,as the usual lack of density
which would be given with a non-staining developer is compensated in
printing by the colour of the negative. For these reasons, and also because
of it's rapid action, it is a great facourite with press photographers. The
yellow stain can be lessened by the addition of 2oz Sodium Suphite (Cryst)
to 20 oz of the "B" solution.

ID-4.
Solution "A"
Metol                      35gr   or    2g
Pot. Metabisulphite       100gr         6g
Pyro                      100gr         6g
Water up to               20 oz         500cc

Solution "B"
Sodium Carbonate (Cryst)  4oz     or    100g
Water up to               20oz          500cc

For use mix equal parts of A & B (ILFORD SELOCHROME 10 minutes @ 65 F)

Page 442
ID-1 (Ilford Pyro-Soda Developer)
This developer is considered by many to be the finest pyro developer ever
formulated.

STOCK SOLUTION.
Pyrogallic Acid           1oz     or    25g
Potassium Metabisulphite  100gr         6g
Water up to               10 oz         250cc
Note** The Pot.Metabisulphite should be dissolved BEFORE the Pyro.

WORKING SOLUTIONS.

SOLUTION "A"
Pyro Stock solution        2oz    or    50cc
Water up to                20oz         500cc

SOLUTION "B"
Sodium Carbonate (Cryst)   2oz          50g
Sodium Sulphite    (Cryst) 2oz          50g
Potassium Bromide (10% solution)
                           2dr          6cc
Water up to                20oz         500cc

For tank use, mix 1 part of the stock solution - 5 parts of "B" and 20
parts water.
**NOTE**
I have used the English spelling for SULFITE and regret that the only
indication of processing times is for Ilford Selochrome, which was rated at
about 125asa and was an Orthochromatic film. HP3 roll film was developed
for 10 minutes @ 65 F, but I don't know how that would equate to modern
emulsions. Some years ago I used ADOX KB14 & KB17 with Pyro with great
success, but these films were VERY slow emulsions. I wish they were still
available, because the KB17 (40asa) was the best 35mm reversible film that
I have ever used.


---
Tom Deering    tdeering@xxxxxxxxxxxx

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