As an introduction to the practical work of lithographic transferring and printing the following description of the autographic method will be found of interest, especially as it bears some similarity to the more difficult process of photo-lithography, and enables everyone possessing a lithographic press and stones to print their own circulars, price lists, &c.
CHAPTER XVIII.
Autography.
THERE are several methods of transferring from specially prepared, or even any strong well-sized paper.[O] As the latter may be most convenient, proceed as follows: Write with autographic transfer ink, readily procurable from dealers in litho requisites; this will keep for years, and may be used with any clean steel pen. After the writing has dried, damp the back of the paper with dilute nitric acid—1 to 3 of water. When the writing is visible through the back of the paper, the sizing has been acted upon sufficiently; the sheet should be placed in a porcelain dish, washed in several changes of water, and blotted off, leaving it evenly damp without being exactly wet. In the meantime a stone should be adjusted upon the bed of the press, rubbed over with pumice powder, and warmed—this may be easily effected by pouring spirits over the stone and igniting it. A suitable scraper—one which, when pressed against the stone, allows no light to pass between, and which should not be wider than the stone—is adjusted in the scraper box. The screw or other appliance for regulating the pressure is then adjusted. The transfer is carefully and accurately placed upon the warm dry stone, with the writing or drawing face downwards in contact with the polished surface, a few sheets of waste paper are placed over the whole, the tympan (the upper surface of which has been freely rubbed with tallow) is lowered into position, the bed is then pushed, with the stone so covered, under the scraper box, so that the scraper may come down, not upon the extreme edge of the stone, but about four or five cm. from the end, lower the scraper (or, according to the construction of the press, raise the bed) and pull through under gentle pressure. Release the pressure of the scraper, withdraw the bed, and raising the corners of the waste sheets used as backing paper, convince yourself that the transfer is in a proper position and has not moved; replace the covering paper, change the position of the stone so that it passes under the scraper in a reversed position, pass through the press again, this time with greater pressure. Repeat these operations three or four times, on each occasion under steadily increasing pressure; remove the transfer carefully by one corner, and allow the stone to become cold; sponge over with thick gum solution, and in this condition it may be left for any length of time. Great care must be taken that none of the tallow used on the tympan, or other grease, comes in contact with the stone, either by the hand, covering paper, or other means.
[O] Transfer paper is more reliable.
If the transfer should exhibit any signs of weakness while the stone is still covered with plain gum water, take, upon a small linen pad, a little ink thinned either with tallow or a few drops of turpentine; by careful rubbing in different directions the lines will be considerably strengthened. Plenty of gum must be kept upon the surface of the stone during this operation, at the completion of which it may be removed with a sponge and water, and the inking-up completed with the roller and the stone gummed in.
Before printing, the gum has to be removed by water, and the stone rolled up with a moderately stiff ink; it is then etched with gum water rendered slightly acid by a few drops of nitric acid. The best test for the acidity of this solution is to add just so much acid to the gum water that, after its application to the edge of the stone for two or three seconds, scarcely perceptible bubbles of carbonic acid gas will show. This is applied evenly to the drawing with a sponge, and allowed to act for a few seconds.
Should the ink “take” to the stone in places other than the design or writing, rub the spot at once with woollen material moistened with gum water; this will clear away the superfluous ink, but the part should be carefully watched during the printing for any recurrence. After the removal of each impression the stone is damped over the whole surface with a damping cloth before another application of the inking roller.