From: Liam Lawless (lawless@ic24.net)
Date: 04/22/00-08:10:29 PM Z
Hi again,
Some stuff from Cassell's (1911). "Sulphocyanide" is the old name for
thiocyanate.
Liam
TONING AFTER FIXING
A method that has been recommended on account of the occasional loss of tone
in the fixing bath after toning. Success depends, as in all toning
processes, upon the quality of the print. Prints intended for fixing before
toning should be deeply printed, fixed, well washed, and then toned in the
ordinary sulphocyanide and gold toner. With some papers, a more satisfactory
system is to immerse the fixed and washed prints in a solution of 1 oz. of
formaline in 9 oz. of water. The toning bath is then used just warm and kept
warm while in use.
TONING AND FIXING COMBINED
A bath very frequently employed for toning and fixing silver prints at one
operation. It is not merely the obvious saving of time and trouble that has
rendered it a favourite method with many workers, but rather the great
advan-tage that the tone or colour of the prints remains the same after
finishing as when taken from the toning bath. In separate toning and fixing,
the colour obtained by toning is frequently considerably modified by the
subsequent fixing. A serious objection to the combined bath is that prints
may be toned to the desired colour before they are properly fixed, and
subsequent fading is the inevitable result. Or the bath may contain sulphur,
and the tones may be due to this substance rather than to gold, and this
also produces prints which will deteriorate quickly.
These objections may be entirely obviated by adopting a suitable formula,
preferably one that contains neither acid nor alum; keeping stock solutions
from which the bath may be prepared when required; mixing sufficient
solution for the prints that are to be toned, and throwing away the mixed
solution after using it once. Using a combined bath many times in succession
is one of the most frequent causes of want of permanence. A reliable formula
and method of working will be found under the heading “Bennett’s Toning Bath
for P.O.P.”
BENNETT’S TONING BATH FOR P.O.P.
A combined toning and fixing bath that gives rich purple tones on most
brands of P.O.P., introduced in 1908 by H. W. Bennett. It con-tains a
sufficiently large proportion of “hypo” to ensure perfect fixation of the
prints, and the bath is rendered slightly alkaline with ammonia. Prints
toned and fixed in this bath are as per-manent as any silver prints; they
preserve their original richness and freshness unimpaired for many years. A
feature of the bath is the fact that separate solutions are kept of each
ingre-dient, and they are so adjusted that equal quantities of each are
taken, excepting the “hypo” solution, and 1 oz. of that is required for each
dram of the others. No calculation is needed, whatever quantity of solution
may be required. Five solutions are necessary
A. Sodium hyposulphite . . 1 lb.
Water, sufficient to make . 32 oz.
The “hypo” should be dissolved in boiling water.
B. Ammonium sulphocyanide . 2 oz.
Water to make . . 8.25 oz.
C. Lead acetate . 1 oz.
Boiling water to make .8.25 oz.
A dense precipitate will settle. The bottle mast be well shaken each time
any solution is required.
D. Gold chloride . . . 15 grs.
Water . . 2 oz. 7 drms.
E. Strong ammonia . . 120 mins.
Water to . 10 oz.
Each solution willkeep indefinitely. To pre-pare the bath, mix together in
the order given:
1 oz. of A, 1 drm. of B, 1 drm. of C, 2 oz. water, 1 drm. of D,and 1 drm. of
B. The measure must be thoroughly rinsed after measuring C and D. The
solution is ready for use in five minutes. This quantity is sufficient for
ten quarter-plate prints; a suitable quantity for any other number may be
prepared by allow-ing 4 oz. of A for every five quarter-plate prints, and
remembering that whatever number of ounces of A solution are taken, the same
number of drams of each of the others will be required. The prints are
immersed in the bath without previous washing, and they should be put in the
solution one at a time, and each one thoroughly wetted before the next is
added. All the prints that are to be toned in one dish should, however, be
put into the solution as quickly as possible consistently with covering each
with the solution evenly.
As soon as the last print is placed in the dish the first should be taken
from the bottom, brought to the top, and quickly examined. Should any
air-bells have formed on the surface they will show as dark marks; but if
they are broken at once with the finger they will not show on the finished
print. The second print that was placed in the bath will now be the lowest;
this should be brought to the top, and so on with each print in turn, until
all have been changed in position. Throughout the operation the same method
of procedure must be followed—the lowest print brought to the top; but after
the first changing the work should proceed more leisurely, leaving each
print a longer time at the top of the solution. The minimum time of
immersion in the bath is twelve minutes in hot weather if the temperature of
the solution is 70 F. (21 C.) or more, and fifteen minutes in cool weather,
though the toning should not be done in a room at a lower temperature than
about 60 F. (21 C.). This minimum time is very important; if less time in
the solution is given, imperfect fixing will result. Longer time may be
allowed if cooler tones are desired; twenty minutes will not be too long. If
warmer tones are required, the composition of the bath must be varied, so
that the desired tones are not reached before the prints are fixed. The
amount of water used for making the B and C solutions may be increased to 11
oz., and for the D solution 3.75 oz., and the bath still pre-pared by taking
1 drm. of each for 1 oz. of A. As soon as the minimum time has elapsed, or
the desired tone reached if longer than the minimum time, the prints are
taken from the bath and at once well washed. If washed in water that is
frequently changed, from one to two hours should be allowed, according to
the frequency of the changes and the quantity of prints in one dish. Prints
for this toning bath require to be very deep.
TONING P.O.P.
Of the two methods of toning and fixing prints on printing-out silver
papers, one is to tone first and afterwards fix, and the other is to tone
and fix at one operation, the second method saving much time and trouble,
while capable of producing quite as good results. It is described under the
heading ‘Toning and Fixing Combined.”
For separate toning and fixing, the prints require first to be washed for
about twenty to thirty minutes in several changes of water; the first two
changes should be made as quickly as possible, care being exercised to
prevent the prints from clinging together. To prepare the toning bath, two
solutions are necessary :—
A. Am. sulphocyanide . 520 grs. 120g.
Water to . 10 oz. 1,000 ccs.
B. Gold chloride . 15 grs. 3.5 g.
Water to . . 3.75 oz. 375 ccs.
To prepare the toning bath, take 2 drms. of A, add 5 oz. of water, and then
add slowly 2 drms. of B; in ten minutes the bath will be ready for use. It
will be sufficient for four whole-plate prints or sixteen quarter-plates. A
proportionate quantity should be prepared for any other number of prints,
allowing always 0.5 drm, each of A and B, and 1.25 oz. of water for each
whole-plate print. The prints to be toned are placed in the solution and
continuously turned over by lifting the lowest print and placing it on top
until the desired colour is reached. They are then rinsed in two or three
changes of water and fixed for fifteen minutes in the following:
Sodium hyposulphite . 1.5 oz. 165 g..
Liquor anunoniae . . 5 mins. 1 cc.
Water . . . 10 oz. 1,000 ccs.
Take care to ensure free access of the solution to the surfaces of the
prints, and to prevent them from clinging together. After fixing, wash the
prints, in water frequently changed, for from one to two hours.
An additional method of toning P.O.P. is by means of platinum. The most
satisfactory manner of working is by first toning with gold, preferably by
the sulphocyanide bath, then, after a short washing, toning with platinum,
washing again, and fixing.
An alternative plan is to use a self-toning paper, by which the operation of
gold toning is avoided, and then the prints are washed, toned simply with
platinum, washed and fixed. Or the prints may be toned first with platinum
and then finished in a combined gold toning and fixing bath.
Formulae for platinum toning baths are given under the heading “Platinum
Toning”; another is:—
Potassium chloroplatinite 1 gr. 0.25 g.
Sodium chloride 10 grs. 2.5 g.
Citric acid . . . 10 grs. 2.5 g.
Water . . . . 5-6 oz. 500-600 ccs.
Whatever method of toning is adopted, only sufficient of the working
solution should be pre-pared for the prints to be toned ; it should be used
once, and then thrown away.
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