CHAPTER II.PAPER TRANSFERS.

Paper for photo-lithographic transfers may be made by coating bank post paper or a good hand-made writing paper, with

Gelatine (Nelson’s)2ounces.Water20ounces.

Put the above into a wide-mouthed bottle or jar, and allow the gelatine to soak until soft; then place the vessel in a large saucepan containing cold water, and set on a fire, or over a gas-burner, and by the time the water in the saucepan is hot the gelatine will be dissolved. Then add slowly (stirring the gelatine with a glass rod) one drachm of a ten-grain solution of chrome alum. Now strain the gelatine solution through fine muslin into a clean dish, standing it in a larger dish containing hot water; float the bank post paper upon this solution (taking care to avoid air-bubbles) for two minutes, then lift it off slowly and hang it up to dry, pinning it by two corners to the edge of a shelf.

When dry, the operation is repeated, but this time the paper is hung up to dry by the two opposite corners, so as to equalize the coat of gelatine.

When dry a second time, it must be floated for two minutes upon

White of5eggs.Water13ounces.

(Shake up well, and filter into a cold dish.)

Paper prepared as above will keep for any reasonable length of time.

For use, it is drawn slowly through a solution composed of

Bichromate of Potash11⁄2ounces.Water20ounces.Alcohol5ounces.Liquor Ammonia10minims.

This being done, the paper is again hung up to dry, this time in a dark room.

When dry, the paper should be laid face down, upon a polished litho. stone, and be pulled through the press three or four times, so as to get the surface as smooth as possible, and insure absolute contact.{133}

This must be done in a yellow light, or in a room lighted by gas or oil light.

The paper is now placed in contact with the negative, in a printing-frame, and exposed to light; the exposure for such paper should be from five to fifteen minutes.

Note well that these paper transfers are printed from negatives taken direct in the camera, without the intervention of the mirror, therefore negatives suitable for printing paper transfers will not do for printing upon zinc, orvice versa.

The progress may be watched by undoing one side of the back of the frame, and examining the image in the dark room; but in damp weather this should not be done too often, as the paper may expand or contract, and blur the image.

The exposure to light under the negative being complete, the print is removed from the frame in the dark room, and is next coated with a thin film of ink as follows:

A smooth litho. stone is carefully coated with a fatty ink by means of a leather roller, extreme care being necessary to insure an even coat of ink over the stone; this being attained, the exposed print is laid face down (the room being lit by yellow light or gaslight) upon the inked stone, then a piece of backing paper laid upon it, and pulled through the press, with a good nip upon it; pull it through twice, then reverse the stone on the press, and again pull through twice, which will leave a fine, thin film of ink upon it. Now take the inked print, and place it in a tray of clean, cold water, allow it to remain therein for five minutes, then lay the print upon a piece of glass, and rub it gently with a pad of cotton-wool—previously wetted in the water. This will remove the ink from those portions of the paper that were protected from the action of light by the opaque portions of the negative, representing the whites of the original.

The application of the pad of cotton-wool is continued until the whole of the picture is cleared from superfluous ink, and the lines composing the image are evenly coated with ink. The ink adheres only to those portions of the paper which the light has acted upon, through the negative.

Now wash the transfer under the tap, then hang it up to dry. When dry it is ready for transferring to stone or zinc.

To transfer to stone or zinc, place the transfer first of all in the damping book, and when limp place it upon a clean, cold, polished stone, and pull it through the press.{134}

When transferred, the image is treated in exactly the same manner as an ordinary transfer on stone or zinc.

The enamelled double transfer paper sold for double transfer carbon work may be used for photo-litho. transfers by floating it upon

Albumen5ounces.Water20ounces.Saturated Solution of Bichromate of Potash3ounces.Liquor Ammonia10drops.

and then dried.

Paper thus prepared must be kept in a dry air-tight case, and just before using is laid face down upon a smooth litho. stone, and pulled through the litho. press. After this, it is placed in contact with the negative in the printing frame, and exposed to light until the details are visible. Although the progress of the action of light can be seen, the frame must not be opened too often, or the paper is apt to expand and blur the image. After exposure the print is inked up, developed, and treated exactly as explained above.

The ink suitable for inking up the stone, previous to laying upon it the exposed print, is composed of

Best Chalk Litho. Printing Ink3parts.Mutton Fat1part.

Put the ink and fat into a small iron or earthenware pot, and place it over a Bunsen burner, or a paraffine stove, or on the hot plate of a kitchen stove (but not over an open fire); allow the heat to melt the two ingredients, stir so as to incorporate them thoroughly; take great care not to allow it to catch fire; if it does, at once extinguish the flame, as the firing would be apt to spoil the ink. When thoroughly melted and incorporated, pour into a tin, or pot, for use when cool; the time occupied in making this ink will not exceed twenty minutes. The mutton fat is obtained by dropping solid kidney suet (shredded) into a pan of clean boiling water, then allowing to cool, when the fat is taken off the surface of the water, freed from damp and stored for use.

Another formula for the preparation of paper, to be inked up, after printing in the same manner as the above transfers, is to coat paper twice with the following preparation, drying between each coat: arrowroot, 1 ounce; wet this thoroughly with 5 ounces of cold water, stirring well with a spatula, adding more cold water, if necessary, to moisten the lot; then pour over it 20 ounces of boiling water, stirring all the time; if, when the 20 ounces are added,{135}the arrowroot has not thickened, add more boiling water until it does do so; now add1⁄2an ounce of powdered bichromate of potash and stir until dissolved; then strain through muslin into a warm dish and float the paper upon it whilst hot, and dry at a temperature of 70° F.

If the bichromate of potash be omitted, the paper may be prepared in quantity and stored away for future use, being made sensitive by floating for five minutes upon

Bichromate of Potash1ounce.Water25ounces.

Paper for either gelatine or arrowroot transfers, after keeping so long after preparation as to be useless, should not be thrown away, but should be again floated upon bichromated gelatine or arrowroot, and after drying will give finer results than new paper.

Prof. Husnik’s photo lithographic transfer paper is obtainable in England and in America. He recommends the following chromate bath:

Bichromate of Ammonium1ounce.Water15ounces.Alcohol4ounces.Liquor Ammonia1ounce.

Keep well corked in a dark place.

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