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Papyrotint

transfer, paper, ink, ounces, stone and ounce

PAPYROTINT PROCESS.—A photo-lithographic process invented by Husband. It is a modification of Captain Abney's improved method of papyrotype. It is specially suitable for the reproduction of subjects in half-tone. The advantage it possesses over other methods are that a transfer can be taken in greasy ink, for transfer to stone or zinc, direct from the negative, the requisite grain being simply obtained by a chemical change. The method is as follows : Any good surface paper is first floated on a bath of Gelatine (Nelson's Flake) 8 ounces Glycerine. ounces Sodium chloride 2 ounces Water so ounces The solution must not be over-heated, and must be free from bubbles. The paper after floating is dried at a temperature of 6o deg. F., and will keep for years. It is sensitized on Potassium bichromate i ounce.

Sodium chloride 5, ounce.

Ferricyanide of potassium loo grains.

Water 30 ounces.

The paper is dried in the dark room, temperature about 7o deg. F. When dry it is exposed under the negative in an ordinary printing frame. Sunlight is preferable. The image will appear on the transfer paper, and when of a dark fawn color on a yellow ground it is sufficiently printed. It is then laid in a bath of cold water for about ten minutes until the soluble gelatine has absorbed its full quantity of water. It is then removed, placed on a flat plate, and all super fluous moisture removed with a piece of blotting paper.

The action of the light has been to render the parts to which it has penetrated through the negative partly insoluble, and at the same time granulated. A hard transfer ink is now com posed of White virgin wax ounce.

/2 Stearine ounce.

Common resin ounce.

These are melted together in a crucible over a small gas jet, and to them are added four ounces of chalk printing ink, and the mixture reduced to the consistency of cream with spirits of tur pentine. A soft sponge is saturated with this mixture and rubbed gently over the exposed paper

(in this stage the nature os the grain can be best seen). An ordinary letterpress roller charged with a little ink from the inking slab is then passed over the transfer, causing the ink to adhere firmly to the parts affected by the light, and removing it from the parts unacted upon. The transfer is next put into a weak bath of tannin and bichromate of potash for a few minutes, and when taken out the surplus solution should be carefully dried between clean sheets of blotting paper. The transfer is hung up to dry, and when thoroughly dry the whole of the still sensitive surface should be exposed to light for about two minutes. A weak solution of oxalic acid (about in zoo) should be used for dampening the transfer, and this applied to the back with a soft sponge. After it has been damped three or four times it is carefully removed and placed between clean sheets of blotting paper. A cold polished stone is then set in the press, and after every thing is ready the transfer is placed on the stone and pulled through twice. The stone or scraper is reversed, and the transfer is again twice pulled through. A moderate pressure and a hard backing sheet should be used, care being taken not to increase the pressure after the first pull through. The transfer is taken from the stone without damping, when it will be found that the ink has left the paper clean. Gum up the stone in the usual way, but if possible let the transfer remain a few hours before rolling up. Do not wash it out with turpentine, and use middle var nish to thin down the ink.