The introduction of films and paper as supports for the sensitive emulsion, whilst it was received with acclamation by amateurs, has after extended trial proved extremely disappointing. The advantages in favour of the new-comers are saving in weight, freedom from halation, and less chance of breakage; but the disadvantages of some extra trouble, some, and often, extremely prolonged operations, in addition to the usual ones of development and fixing, have and still out-weigh the above advantages. The writer has used every film and negative paper in the market, and has given them all a fair trial, but still adheres to the old standard dry-plate. Films are recommended, especially for those engaged in photo-mechanical or carbon printing, as they can be printed from either side, but as the same effect may be obtained by the use of the ordinary dry-plate, with no more trouble than is required for a film, the writer prefers even for this work to use the trusty and reliable glass support.
The first introduced was the negative paper, which, as its name implies, consisted of an emulsion upon an almost grainless paper, but it was found to be impossible to totally eradicate the grain, hence another support, such as a film of insoluble gelatine or a temporary support of paper was invented.
It is of course obvious that some mechanical method is required to strain the paper flat in the dark slide, or from the natural tendency of the paper to curl or bend up the picture would be out of focus. For this purpose an ingenious carrier has been devised, which is extremely simple and reasonable in price, but when on a tour it is of great convenience to be able to expose on as many subjects as one may desire without having resource to the dark room for the purpose of changing the films. They are therefore sent out in long bands of sensitive tissue on rollers, which by an ingenious arrangement can be exposed in successive portions till the whole is exposed. The arrangement by which these bands of emulsion can be manipulated is termed a roller slide, and whilst there are many such in the market, the writer has no hesitation in recommending as the simplest and the best that called the Optimus, which, unlike all others, requires no alteration of the focussing screen, but is simply inserted as an ordinary dark slide. It possesses also a special checking apparatus, which makes it impossible to wind off more than is required for one exposure, and also an automatic registering contrivance, which makes it absolutely self-chronicling, and impossible to cut the paper, except in the right place,
For developing the different kinds of films, the processes are precisely the same as for dry-plates, and the beginner may either use the method and the solutions for developing recommended at page 27, or he may employ the following which is perhaps an improvement: -
Metabisulphite of Potash...... 480 „
Distilled water to make 15 ounces of solution.
Bromide or Restraining Solution. Ammonium Bromide ... ••• 480 grains. Distilled water to make 4 ounces of solution.
Liq. Ammonia, 880......... 1 ounce.
Distilled water ......... 9 ounces.
Potash and Soda Accelerator.
Carbonate of Potash ...... 480 grains.
„ Soda ... ... ... 480 ,,
Ferrocyanide of Potash ...... 480 „
Distilled water to make 10 ounces of solution.
Hydrokinone may also be used and is one of the best developers for a beginner, as it is practically free from stain, and gives much latitude of exposure; or the Ferrous Oxalate Developer, recommended on page 28, may be used.
Hydrokinone or Quinol is one of the best developers for a beginner, as it is suitable alike for negative and positive work, and is practically free from the staining proclivities both of hands and film, so characteristic of Alkaline Pyro. It possesses also the great advantage of being especially a developer which will correct to a great extent any errors in exposure, as by the judicious use of this reducing agent, great over-exposure may be corrected and negatives of good printing density be obtained, and likewise for under exposure it enables one to obtain a much better result than with Pyro, developing all possible detail, with no risk of fog if properly used; it is in this respect far superior to Pyro or Ferrous Oxalate. Full instructions are given on page 91.
As most of the commercial films and paper negatives differ slightly in their manipulation, a short resume of the process for each may be of some assistance.
This consists of an insoluble sensitive film of gelatine emulsion attached temporarily to a paper support.
Immerse the film face downwards in a dish of clean cold water, taking care that no air bubbles adhere to it. When thoroughly limp, place face upwards in a developing dish, and pour on the developer, and proceed with development as recommended at page 27. When development is completed, rinse in two or three waters, and then fix in the following fixing-bath: -
Hyposulphite of Soda ...... 4 ounces.
Water ... .... .... .... .... 16 "
It is absolutely necessary for film-work of any kind that no alum or any other chemical should be added to the fixing-bath. When thoroughly fixed, which will be in about ten or fifteen minutes, wash in the tank provided for that purpose, or by placing in a stream of running water. Leave it washing for half-an-hour, and clean a glass-plate, a little larger all round than the negative film, and coat it with the following solution:-
Masticated India-rubber...... 10 grains.
Benzole ... ... ... ... 1 ounce.
Allow it to dry for about five minutes, and then coat with enamel collodion, made as follows: -
Pyroxylin............ 6 grains.
Methylated Spirit......... 1-ounce.
„ Ether ... ... ... ½-ounce.
When the collodion has set, that is, when it will not drop from a corner of the plate, wash it thoroughly under the tap till the surface no longer repels water, or till the water runs off without any sign of greasiness; now place the collodionised plate face upwards in a dish of cold water, bring the negative film into contact with it under the surface of the water, lift both out, and place film upwards on a pad of blotting-paper, lay a sheet of blotting-paper over it, and squeegee into close contact, using considerable pressure in all directions to wipe off superfluous water. Now place the film between sheets of blotting-paper for fifteen minutes, when it will be ready for the stripping process. For this operation, immerse the glass-plate bearing the film into a dish containing water at about 150 deg. to 200 deg. Fahr. temperature, rock the dish slightly, and the paper will be found to gradually float off; it should be entirely removed, and all adherent portions of soluble gelatine removed by brushing with a camel's hair brush or tuft of cotton wool. Now wash the film in cold water, and immerse in the clearing bath of alum and citric acid recommended at page 29. After thoroughly washing in running water for about two hours the film is ready for transfer to its final support, for which purpose a special stripping skin is prepared, which must be soaked in water for two minutes, not longer; the film is brought in contact with it under water and squeeged into optical contact, and set aside to dry for four or five hours, after which period the edges may be trimmed with a knife, and the film easily stripped from the glass.