[Footnote 1: A communication to the Birmingham Photographic
Society.]
Having had a certain measure of success with Eastman stripping films,
I have been requested by your council to give a paper this evening
dealing with the subject, and particularly with the method of working
which my experience has found most successful. In according to their
request, I feel I have imposed upon myself a somewhat difficult task.
There is, undoubtedly, a strong prejudice in the minds of most
photographers, both amateur and professional, against a negative in
which paper is used as a permanent support, on account of the
inseparable "grain" and lack of brilliancy in the resulting prints;
and the idea of the paper being used only as a temporary support does
not seem to convey to their mind a correct impression of the true
position of the matter.
It may be as well before entering into the technical details of the
manipulation to consider briefly the advantages to be derived--which
will be better appreciated after an actual trial.
My experience (which is at present limited) is that they are far
superior to glass for all purposes except portraiture of the human
form or instantaneous pictures where extreme rapidity is necessary,
but for all ordinary cases of rapid exposure they are sufficiently
quick. The first advantage, which I soon discovered, is their entire
freedom from halation. This, with glass plates, is inseparable, and
even when much labor has been bestowed on backing them, the halation
is painfully apparent.
These films never frill, being made of emulsion which has been made
insoluble. Compare the respective weights of the two substances--one
plate weighing more than a dozen films of the same size.
Again, on comparing a stripping film negative with one on glass of the
same exposure and subject, it will be found there is a greater
sharpness or clearness in the detail, owing, I am of opinion, to the
paper absorbing the light immediately it has penetrated the emulsion,
the result being a brilliant negative. Landscapes on stripped films
can be retouched or printed from on either side, and the advantage in
this respect for carbon or mechanical printing is enormous. Now,
imagine the tourist working with glass, and compare him to another
working with films. The one works in harness, tugging, probably, a
half hundredweight of glass with him from place to place, paying extra
carriage, extra tips, and in a continual state of anxiety as to
possible breakage, difficulty of packing, and having to be continually
on the lookout for a dark place to change the plates, and, perhaps, on
his return finds numbers of his plates damaged owing to friction on
the surface; while the disciple of _films_, lightly burdened with only
camera and slide, and his (say two hundred) films in his pockets, for
they lie so compact together. Then the advantages to the tourists
abroad, their name is "legion," not the least being the ease of
guarding your exposed pictures from the custom house officials, who
almost always seek to make matters disagreeable in this respect, and
lastly, though not least, the ease with which the negatives can be
stowed away in envelopes or albums, etc., when reference to them is
easy in the extreme.
Now, having come (rightly, I think, you will admit) to the conclusion
that films have these advantages, you naturally ask, What are their
disadvantages? Remembering, then, that I am only advocating stripping
films, I consider they have but two disadvantages: First, they entail
some additional outlay in the way of apparatus, etc. Second, they are
a little more trouble to finish than the glass negatives, which sink
into insignificance when the manifold advantages are considered.
In order to deal effectively with the second objection I mentioned,
viz., the extra trouble and perseverance, I propose, with your
permission, to carry a negative through the different stages from
exposure to completion, and in so doing I shall endeavor to make the
process clear to you, and hope to enlist your attention.
The developer I use is slightly different to that of the Eastman
company, and is as follows:
A.
Sulphite of soda. 4 ounces.
To be dissolved in 8 ounces of hot distilled water, then rendered
slightly acid with citric acid, then add--
Pyrogallic acid. 1 ounce.
Water to make up to 10 ounces.
B.
Pure carbonate of soda. 1 ounce.
Water to make up in all to 10 ounces.
C.
Pure carbonate of potash. 1 ounce.
Water to make up to 10 ounces.
D.
Bromide of potassium. 1 ounce.
Water to make up to 10 ounces.
I have here two half-plate films exposed at 8:30 A.M. to-day, one with
five and one with six seconds' exposure, subject chiefly middle
distance. I take 90 minims A, 10 minims D, and 90 minims B, and make
up to 2 ounces water. I do not soak the films in water. There is no
need for it. In fact, it is prejudicial to do so. I place the films
face uppermost in the dish, and pour on the developer on the center of
the films. You will observe they lie perfectly flat, and are free from
air bubbles. Rock the dish continually during development, and when
the high lights are out add from 10 to 90 minims C, and finish
development and fix. The negatives being complete, I ask you to
observe that both are of equal quality, proving the latitude of
exposure permissible.
I now coat a piece of glass half an inch larger all round than the
negative with India rubber solution (see Eastman formula), and
squeegee the negative face downward upon the rubber, interposing a
sheet of blotting paper and oilskin between the negative and squeegee
to prevent injury to the exposed rubber surface, and then place the
negative under pressure with blotting paper interposed until
moderately dry only.
I then pour hot water upon it, and, gently rocking the dish, you see
the paper floats from the film without the necessity for pulling it
with a pin, leaving the film negative on the glass. Now, the
instructions say remove the remaining soluble gelatine with camel's
hair brush, but, unless it requires intensifying, which no properly
developed negative should require, you need not do so, but simply pour
on the gelatine solution (see Eastman formula), well covering the
edges of the film, and put on a level shelf to dry.
I will now take up a negative in this state on the glass, but dry, and
carefully cut round the edges of the film, and you see I can readily
pull off the film with its gelatine support. Having now passed through
the whole of the process, it behooves us to consider for a few minutes
the causes of failure in the hands of beginners and their remedies: 1.
The rubber will not flow over glass? Solution too thick, glass greasy.
2. Rubber peels off on drying? Dirty glass. 3. Negative not dense
enough? Use more bromide and longer development. 4. Gelatine cracks on
being pulled off? Add more glycerine. 5. Gelatine not thick enough?
Gelatine varnish too thin, not strong enough. 6. Does not dry
sufficiently hard? Too much glycerine.--_E.H. Jaques, Reported in Br.
Jour. of Photography._
* * * * *
HOW DIFFERENT TONES IN GELATINO-CHLORIDE PRINTS MAY BE VARIED BY
DEVELOPERS.
The following formulæ are for use with gelatino-chloride paper or
plates. The quantities are in each case calculated for one ounce,
three parts of each of the following solutions being employed and
added to one part of solution of protosulphate of iron. Strength, 140
grains to the ounce.
_Slaty Blue._
1.--One part of the above solution
to three parts of a solution of citrate of ammonia.
_Greenish Brown._
2.--Citric acid. 180 grains
Carbonate of ammonia. 50 "
3.--Citrate of ammonia. 250 grains.
Chloride of sodium. 2 "
4.--Citrate of ammonia. 250 grains.
Chloride of sodium. 4 "
_Sepia Brown._
5.--Citrate of ammonia. 250 grains.
Chloride of sodium. 8 "
_Clear Red Brown._
6.--Citric acid. 120 grains.
Carbonate of magnesia. 76 "
_Warm Gray Brown._
7.--Citric acid. 120 grains.
Carbonate of soda. 205 "
_Deep Red Brown._
8.--Citric acid. 120 grains.
Carbonate of potash. 117 "
_Green Blue._
9.--Citric acid. 90 grains.
Carbonate of soda. 154 "
Citrate of potash. 24 "
Oxalate of potash. 6 "
_Sepia Red._
10.--Citric acid. 80 grains.
Carbonate of soda. 135 "
Citrate of potash. 12 "
Oxalate of potash. 3 "
11.--Citric acid. 108 grains.
Carbonate of magnesia. 68 "
Carbonate of potash. 12 "
Oxalate of potash. 3 "
_Sepia Yellow._
12.--Citric acid. 40 grains.
Carbonate of magnesia. 25 "
Citrate of ammonia. 166 "
13.--Citric acid. 120 grains.
Carbonate of magnesia. 72 "
Carbonate of ammonia. 72 "
Chloride of sodium. 8 "
_Blue Black._
14.--Citric acid. 120 grains.
Carbonate of ammonia. 70 "
Carbonate of magnesia. 15 "
15.--Citric acid. 120 grains.
Carbonate of magnesia. 38 "
Carbonate of ammonia. 44 "
16.--Citric acid. 90 grains.
Carbonate of magnesia. 57 "
Citrate of potash. 54 "
Oxlate of potash. 18 "
17.--Citric acid. 72 grains.
Carbonate of magnesia. 45 "
Citrate of potash. 54 "
Oxalate of potash. 18 "
18.--Citric acid. 60 grains.
Carbonate of magnesia. 38 "
Citrate of potash. 68 "
Oxalate of potash. 22 "
_A more Intense Blue Black._
19.--Citric acid. 30 grains.
Carbonate of magnesia. 18 "
Citrate of potash. 100 "
Oxalate of potash. 33 "
_A Clearer Blue._
20.--Citrate of potash. 136 grains.
Oxalate of potash. 44 "
In the photographic exhibition at Florence, the firm of Corvan[1]
places on view a frame containing twenty proofs produced by the
foregoing twenty formulæ, in such a way that the observer can compare
the value of each tone and select that which pleases him best.--_Le
Moniteur de la Photographie, translated by British Jour. of Photo._
[Footnote 1: Does this mean Mr. A. Cowan?--_Translator._]
* * * * *