Liam Lawless (lawless@vignette.freeserve.co.uk)
Wed, 26 May 1999 01:26:44 +0100
Hi Folks,
Richard points out that the recipe I quoted was in fact Nelson's. Sorry! I
do, actually, remember reading somewhere that hypo-alum toned prints should
be fixed, but cannot remember where, or what reason was given. As stated
earlier, I disposed of many books a while ago and don't now have very much
info on toning, but Mallinckrodt's Chemistry of Photography (6th. ed.,
1940), which Judy sent me, says something. For straight hypo-alum, it does
not mention fixing, but does say to make sure that prints are fully toned, I
would guess because colloidal sulphur is inevitably trapped in the emulsion,
which would continue to tone over time if there remains silver for it to act
upon.
Mallinckrodt gives Nelson's, plus two other hypo-alum-gold recipes (for
Defender and Haloid papers). These recipes (which are, in fact, identical!)
are of a different type to Nelson's, and a fix is specified for both. I'll
just quote the Defender version, along with notes from the text, and what
the Haloid Co. has to say about using the same formula. (If anyone's paying
attention, this recipe also looks very like the Walley recipe -as far as I
can remember it - which I mentioned in my last post, and which didn't
impress me very much on the papers of about 10 years ago. But don't let
that discourage you - I might not have mixed it properly!)
HYPO-ALUM-GOLD SEPIA METHOD
For even richer colours than the above process (which, if you don't have the
book, was hypo-alum without gold), a soluble gold salt such as gold chloride
or gold sodium chloride is added to a solution containing hypo, alum, and
"ripener".
A small quantity of gold is deposited so that the final toned image consists
of a mixture containing silver sulphide plus a small amount of gold.
Satisfactory and pleasing colours are dependent upon the size of the gold
particles in the mixture. When deposited slowly, the gold is in a very
finely divided state having a reddish cast not as desirable as the blue gold
obtained with the coarser particles by quick deposition.
To insure rapid deposition, the bath must be alkaline and sodium phosphate,
a mild alkali, is used to neutralise the excess acid in the solution, before
the gold salt is added. Most formulas recommend a definite test with red
litmus paper which turns blue in alkaline solution. [I know you know that,
but I'm quoting!]
DEFENDER PHOTO SUPPLY CO., INC.
This formula is recommended for Defender Artura. By this method the colour
of the black and white print does not govern the colour of the sepia.
Develop and fix the B&W print in the regular way, wash prints a few minutes
to eliminate acid from the hypo bath and tone in the following:
Sol. No. 1
A Boiling water (dist.) 128 oz.
Hypo 16 oz.
Potassium alum 2 oz.
Boil the above 2 minutes, cool and add:
Sod. phosphate 2 oz.
Test with red litmus. If it does not turn blue within 1 minute, heat again
and add sod. phosphate in 2 oz. quantities until the bath has become
slightly alkaline. Then dissolve:
B Silver nitrate 60 grains
Water 1 oz.
Pot. bromide 180 grains
Water 1 oz.
Separate solutions are made of the silver and bromide, each dissolved in 1
oz. of water. The bromide solution is then poured into the silver solution.
The resulting mixture, precipitate and all, is then added to the hypo-alum
bath after the latter has thoroughly cooled.
Sol. No. 2
Gold chloride 15 grains
Water 2 oz.
To use, add 1 dram of gold solution to each 16 oz. of hypo-alum bath, tone
at 90 to 110 deg. F, not higher than 110 deg. F. Prints should be examined
as the toning proceeds, and removed when the desired tone is reached.
128 oz. of sepia toning bath will tone about 1 gross of 4X6 prints. When
used up to this point, discard and mix a fresh bath. All prints should be
toned at one time. Prints should be separated in the toning bath. After
toning, sponge to remove any surface sediment, FIX THEM AGAIN IN ACID HYPO
BATH FOR 5 MINUTES and wash in the same manner as black and white prints.
_________________
OK, that's Defender. Haloid gives the same ingredients and quantities, but
slightly different mixing instructions (e.g. instead of "dissolve in 128
oz", "dissolve in 64 oz. and top up with 64 oz. water"). What they say
about it is:
Prints to be toned by this process should be fully exposed, so that
development to proper depth may be obtained without forcing. Use plenty of
bromide in developer, for prints having pronounced olive will tone more
readily. Care should be used in preparing the toning bath, for it is so
balanced as to be just slightly alkaline. An acid bath will not work
satisfactorily.
Then follows the recipe, and:
To tone, add 1 oz. of the gold solution to 1 gallon of bath. Place all
prints to be toned into bath at once. Tone until desired colour is
obtained, then CHECK BY IMMERSING IN THE ACID HYPO BATH FOR ABOUT 5 MINUTES.
THIS IS IMPORTANT.
One gallon of bath will tone 1 gross of 4X6 paper, or equivalent. If more
prints are to be toned, more gold should be added. Sponge to remove
sediment; washing and drying may be done in the usual manner.
________________________
Still doesn't exactly say why to fix (apart from "checking" toning), but
hope that helps. One other thought occurs to me: I don't know if there
actually is any hypo in hypo-alum, because it may be that all the sulphur is
precipitated from it, in which case it probably doesn't have any fixing
properties. When toning with gold, there is some conversion of silver to
silver chloride which, it could be, remains after hypo-alum toning.
As a matter of interest, the same book gives a Gevaert recipe (GT2) which is
also stated to give warmer tones than the plain hypo-alum formula (GT1), but
using lead nitrate instead of gold.
Liam
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