Solutions used in developing the film should not exceed a temperature of 75 deg. Fahr., and the fingers should only touch the films at the corners while wet. Printing from these films may be done from either side, but that which was in contact with the glass at the time of the transfer is the right one. Ground-glass placed in the printing frame with the ground-glass towards the negative will keep the film flat, and give very soft effects.
The paper is first soaked in water and then developed as above, well washed and placed in an alum bath, - composed of alum 2 oz., water 20 oz., - for 5 or 10 minutes, well washed and then placed in a fixing bath. After thorougly washing again it can be placed in an alum and citric acid clearing bath and dried, which is best done by mounting it on collodionised glass, as described under Eastman's Film. It will be found that a further operation for making the paper transparent is required, and for this purpose vaseline or vaseline oil, which can be obtained from any chemist, should be freely applied to the paper, and then the negative is left in a warm room for about 12 hours to allow the oil to soak into the pores of the paper. After the lapse of 12 hours excess may be wiped off by a tuft of cotton-wool or flannel. To store these oiled negatives they should be preserved between sheets of paper impregnated with stearine, which can be obtained from any chemist.
Notwithstanding the introduction of the above-mentioned films, manufacturers have been for some time in search of a support even more satisfactory which should require no stripping, and no extra processes. And at the commencement of this year (1889), films were introduced, made of celluloid. Their treatment differs practically in no way from glass plates, except that they should be allowed to soak in water for about thirty seconds prior to development, and with Ouinol development, at least double that time. If the amateur has mastered the principles laid down in the previous chapter on development (pp. 18 - 39), he will have no difficulty in successfully developing these films. After fixing and washing, a five minutes' immersion in the following bath will be found beneficial: -
Glycerine, ½oz.; water, 100 oz.
After soaking, pass a tuft of cotton wool over the surface of film, to absorb adherent solution, and allow to dry by hanging up from one corner. When the surface is dry lay the film face down on clean paper, and clean the back of the film with a soft cloth, or pad of flannel.