494 



LITHOGRAPHY. 



starch over it with a fine brush, or camel's hair 

 pencil. Parchment glue is preferable to starch. A 

 superior kind of paper is made by taking thick 

 unsized paper, and covering it with a thick solution 

 of the following ingredients : 



Flour starch, 

 (,iini Arabic, 

 Alum, 



120 parts. 

 40 

 20 



The paper may be tinted by adding a small quan- 

 tity of gamboge or Avignon seed. The composition 

 must be laid on while hot, and the paper must be 

 afterwards smoothed by being passed through the 

 press. The lithographers in Paris employ rice 

 paper for transferring sketches: the paper being, 

 of course, covered by a thin coating of the starch 

 composition. 



Much of the beauty of chalk prints will depend 

 upon the good quality of the chalk pencils or cray- 

 ons. The following composition has been found to 

 answer the purpose admirably: 



Dried tallow soap, 

 White wax, 

 Lamp black, . 



150 parts. 

 150 

 25 



The first two of these ingredients are mixed and 

 melted in a copper vessel over a brisk fire ; they are 

 constantly stirred, the lamp black being added by 

 little and little. The compound, while hot, is poured 

 into the brass crayon mould, of which we have 

 already spoken, the mould having been previously 

 oiled to prevent the crayons from adhering. 



The lithographic printing ink, is prepared in a 

 similar manner to the ink employed by the letter- 

 press printers. A quantity of linseed oil is boiled in 

 a copper or brass vessel, until it burns when set fire 

 to by a lighted paper, being kept burning till it is 

 reduced in volume, by losing from one fourth to 

 one half of its original bulk. The oil requires to be 

 stronger for working crayon, than for working litho- 

 graphic ink drawings. Regarding the thickness of 

 the ink, experience alone can be the guide. 



The lamp black used, should be that produced by 

 the burning of rosin, when the ink is intended to be 

 black. If the ink is intended to be blue, then Prus- 

 sian blue or indigo is used, if red, vermilion and other 

 colouring matters may be used, some of which must 

 be mixed with oil of turpentine before they combine 

 with the boiled oil. 



There is a kind of ink used for preserving the 

 drawing or writing upon the stone when the working 

 is to be suspended for eight or ten days it is callee 

 preserving ink. An excellent preserving ink is com- 

 posed of, 



Boiled oil, very thick . . 2 parts 



Sheep's fat . . . .4 



White wax . 1 



Oil of turpentine . .1 



Lamp black. . .4 



The first three ingredients are brought to boil in a 

 vessel over the fire, the turpentine is then added, anc 

 the lamp black by little and little, the mixture being 

 constantly stirred. A table and roller must be kep 

 for this ink alone. 



When the paper to be used in printing is sized, i 

 must be damped the night before use, in the same 

 manner as is done by the letterpress printers, one 

 sheet is passed through water and laid upon a table 

 ten or twelve dry sheets are laid above it, another 

 wet sheet is laid above these, then dry ones, &c. 

 the whole being pressed down by a board, anc 

 weights for two or three hours. But it is better tha 

 the paper should contain little or no size, in whicl 

 case it does not require to be damped. The greates 

 care should be taken not to use paper made fronr 

 rags that have been bleached with chloride of lime 

 By the use of such paper, the drawing will be inevita 



>ly spoiled. Chinese paper, which is impregnated with 

 iliiin, lias a like effect. 



In order to place a chalk drawing on the stone, 

 he outline may be traced upon it with a black lead 

 pencil, or what is still better with rod chalk, taking 

 :are to lean very lightly. A still better method is 

 to trace the outline with red chalk on a piece of 

 paper : the stone is nibbed with a little turpentine, 

 .he paper laid on it wetted a little, and covered with a 

 second sheet; the tympan is brought down upon it, 

 and it is passed twice or thrice througli the press, 

 and the outline is transferred from the paper to the 

 stone. Another method is to place a bit of rice 

 paper on the stone, the paper having been previously 

 rubbed with red lead. On this the drawing is laid, 

 and the outline traced with a steel point. In filling in 

 the outline and forming the shades, the artist proceeds 

 with his crayon in the same way as he would upon 

 paper. There is, however, much greater difficulty in 

 keeping a point in the lithographic drawing, and con- 

 siderable practice is necessary to attain a sufficient 

 freedom of hand. The proper depth of stroke should 

 be given at first, as it is not easy to deepen it by re- 

 touching. While putting in the light tint, the chalk 

 must be fixed into a light reed, the metal port-crayon 

 being too heavy, and it is very difficult to bring the 

 finer tints oft' well in the impression. A wedge 

 shape is better than the point for the crayon, being 

 less liable to break ; when pieces do break off, they 

 must be carefully brushed away. As the chalk 

 softens by the warmth of the hand, several pieces 

 must be had in readiness to be used in succession. 



In drawing with ink, the fine steel pen is used. 

 The ink which has been cut into sticks, is now placed 

 in a cup that has been previously warmed, hot water 

 is poured upon it, and it is melted to such a degree 

 of nuidity as will enable it to flow easily from the pen; 

 but the dilution must not be carried further, as the 

 lines laid on by the pen must be sound. The only 

 way of varying the depth of shade or tint, is by draw- 

 ing the lines of different degrees of thickness, or by 

 regulating their distance from one another. 



In drawing on the stone, either with crayons or 

 ink, the greatest attention must be paid to keep the 

 stone clean ; it must not be touched by the draughts- 

 man's hand, nor should he even breathe upon it. 



The next mode we shall notice, of placing the 

 writing of figures to be printed upon the stone, is by 

 the transfer paper we formerly noticed. The paper 

 being prepared as was stated with the starch com- 

 position, is commonly rubbed over with a little pow- 

 dered gum sandarac, after which the writing or draw- 

 ing is executed with an ink of greater thickness than 

 that used in writing upon the stone. When the trans- 

 fer paper has been prepared, the stone is heated to 

 a temperature of somewhat above 100* and laid on 

 the table of the press. The paper is damped, and 

 ere the stone is cold, it is laid on it, and passed 

 several times through the press, by which means the 

 writing is transferred. 



The drawing being by any of these means put upon 

 the stone, it is placed obliquely over a tank, and a 

 weak solution of nitric acid poured upon it. The 

 stone is reverted, that is, the under edge is next 

 placed uppermost and the dilute acid is again poured 

 upon it. From the nature of the stone, this solution 

 will cause it to effervesce : the strength of the solution 

 should in general be about one part of acid to one 

 hundred of water. The stone is now washed with 

 rain water, after which gum water is poured upon it. 

 The roller well charged with printing ink, is now 

 passed over it in various directions until the drawing 

 is completely inked, after which the stone is laid 

 over with a solution of gum arabic of about the con- 

 sistence of oil. Great nicety is required in this pro- 



