: Practical Lithography by Seymour Alfred - Lithography Technique; Photolithography

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The composition used for coating copperplate transfer paper must possess a somewhat heavy body, and for this reason plaster of paris enters into its composition, which is as follows:--

Plaster of paris 2 lb. Flake white 1 lb. Flour 2 lb. Fish glue 1/4 lb. Alum 1 oz.

Soak the alum and glue from 8 to 10 hours, and then boil them until they are dissolved. Make the flour into a smooth paste by the addition of a little water, and mix it with the flake white. Mix the plaster of paris with water, and stir continuously until it becomes incapable of setting. Add the other ingredients, already mixed, and see that they become thoroughly incorporated with the plaster of paris, after which coat the paper twice with the mixture.

The following may be substituted for the above:--

Plaster of paris 2 lb. Flour 2 lb. Gelatine 4 oz.

A transfer paper with its surface granulated to represent a mechanical stipple, or the texture of a grained stone, may be prepared in the following manner. Take of:--

Starch 9 oz. Parchment chippings 12 oz. Flake white 14 oz.

Prepare the starch as previously described, and dissolve the isinglass by boiling. Mix the flake white into a thin paste by the addition of water. Warm the three ingredients, and mix the whole thoroughly. Coat a fairly heavy printing paper twice with this composition, and when it is thoroughly dry give it the required granulation by means of grained stones or engraved plates. The grain thus imparted breaks up the drawing into a series of minute dots. Paper of this description is most suitable for pencil or crayon work. Its usefulness is obvious. It enables the artist to use his chalks in the usual manner, without the inconvenience of handling large stones. No graining of the stone is necessary, and the grained effect can be confined to any portion of the design.

Photo-litho transfer paper is in every respect a specific article, the coating of which consists of a gelatinous emulsion, which can be readily sensitised, and upon which a photographic image can be developed. Special preparation and manipulation are therefore necessary in connection with its production, and these points will be fully dealt with in a subsequent chapter.

One more variety of transfer paper should be mentioned, namely, the diaphanic, which possesses excellent qualities for certain classes of work. It is very transparent, and extremely useful in the tracing of key formes, or for making facsimile drawings for immediate transference to stone.

COPPERPLATE TRANSFER PRINTING

The Copperplate Press--The Operation--Charging the Engraved Plate--Cleaning-off and Polishing--Making the Impression-- Useful Notions.

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