The method in this case differs somewhat from the preceding. First melt the bitumen and then add the wax and soap in small pieces as before. Burn this for fifteen minutes, and add the shellac, balsam, and black, boiling the whole gently for forty minutes. Mould into squares or sticks, and for convenience in handling cover these with tinfoil.
Should an extra powerful ink be required for shading or stippling films, the stone-to-stone re-transfer ink can be reduced to a working consistency with castor oil instead of varnish, and thus rendered suitable for this purpose.
CHAPTER III
Lithographic Transfer Papers
Essential Features—Varnish Transfer Paper—Damp-stone Transfer Paper—French Transparent Transfer Paper—Copperplate Transfer Paper—An Alternative Recipe—Granulated Papers—Photo-litho Transfer Paper.
Transfer papers are even more used than the transfer compositions already described, and in greater variety, in consequence of which there is a wide difference of opinion concerning their merits.
To a certain extent the specific value of any transfer paper must depend upon local conditions. That which might be of the utmost value to one printer would in all probability fail to meet the requirements of another. With these also, as with the transfer inks, the main point is to grasp the general principles involved. Adhering to these principles enables any intelligent workman to adapt the transfers to his own peculiar necessity. It is most important that lithographic transfer paper should be absolutely impervious to the transfer composition or ink, so that an impression of full strength can be conveyed to the stone, leaving its greasy properties unimpaired. The paper therefore must undergo special preparation, and here again the character of the work and the conditions under which it is carried out are the chief controlling elements. So much is this the case that many lithographic printers prefer to make their own transfer paper, and find such a procedure eminently satisfactory.