SILK, PRINTING ON. —Photographic positives can be made very effective printed upon silk, satin, or other fabrics. There are several methods of accomplishing this. A simple one is the following: The silk best suited for the purpose is that known as Chinese silk, and this is first washed in warm water with a plentiful lather of soap, then rinse in hot water, and gradually cool until the final washing water is quite cold. Next prepare the following solutions : The arrowroot is mixed up into a paste with a little of the distilled water, and the remainder added boiling hot, with the acid and the salt previously dissolved in it. When the solution is quite clear the tannin solution is added, and the whole allowed to get fairly cool. The silk is then immersed for about three minutes, being kept under without air in the folds, and then hung up to dry, or stretched out with pins on a flat board. The material is then sensitized by brushing over with the following solution: Silver nitrate 12 parts Distilled water ion parts Nitric acid, two drops to every three ounces.
Other methods of sensitizing are by immersing in or floating on the silver solution. After sensi tizing, the material is dried by pinning on to a board to keep flat. It is then cut up as required, and printed behind the negative. Every care must be taken in printing to keep the material flat, and without wrinkles or folds. It must also be kept quite straight, otherwise the image will be distorted. Printing is carried on in the same manner as with albumenized paper. It is then washed and toned in any toning bath. The sulphocyanide gives the best action. Fix in a ten
per cent. solution of hyposulphite of soda for ten minutes, wash and dry spontaneously. When just damp it is ironed out flat with a not over-heated iron. Black tones can be obtained with a platinum toning bath, or with the uranium and gold toning bath made up as follows: Gold chloride r part Uranium nitrate t part Dissolved and neutralized with sodium carbonate, and then added to Sodium chloride 16 parts Sodium acetate i6 parts Sodium phosphate 16 parts Distilled water. 4,00o parts Very effective results may be made by printing with wide white margins obtained by exposing with a non-actinic mask.
Another method is the following : Ammonium chloride loo grains Iceland moss 6o grains Water (boiling) 20 ounces When nearly cold this is filtered, and the silk immersed in it for about fifteen minutes. To sensitize immerse the silk in a 20 grain solution of silver nitrate for about sixteen minutes. The silver solution should be rather acid.
Or immerse the silk in- Water... ounce Sodium chloride 5 grains Gelatine 5 grains When dry float for thirty seconds on a 50-grain solution of silver nitrate. Dry, slightly over-print, and tone in the following bath : Gold chloride 4 grains. Sodium acetate 2 drachms.
Water 29 ounces.
Keep twenty-four hours before using. Fix for twenty minutes in hypo, 4 ounces to the pint of water.
Images in many different dyes may be made upon silk by the Diazotype process. (See Primuline Process.) Instead of silk, satins and other similar fabrics can be used.