The Invention of Lithography

by Alois Senefelder

What has happened is that the wet rubbing has cleansed the surface of the stone of all its fat and at the same time has polished it and made it slippery. It is a sort of preparation; and though the fat of the ink has penetrated into the interior of the stone, the accidental preparation still offers an obstacle which prevents the printing-ink from adhering to the fat in those places. As I will show, these places can be prepared again thoroughly.

(b) Another case is when the design is too weak, and has been attacked by the etching-fluid too powerfully, though without being destroyed. Here the printing-color usually is removed by the ink-roller, even though it adheres pretty well when being wiped.

(c) A third kind of imperfect preparation is when a stone inclines to take color or smut on prepared places. This happens sometimes in part, sometimes over the whole surface, which latter effect is described by saying that the stone has acquired a tone.

The cause of this phenomenon may be one of many. It is either due to the appearance of a fat that has been in the stone, or to the fact that unskilled manipulation has destroyed the preparation partially.

Thence follow several observations again:—

(1) Mere wiping with clean water will give the stone a sort of preparation if the material used for wiping is suitable. This preparation is incomplete, but can be transformed very easily into a complete one. This incomplete preparation is according to the strength with which the rubbing material affects the stone. Linen and cotton stuffs have the least effect. More potent are animal wools and hair, silk or wet leather. The printing-color itself has a preparing property if it is made of very tough varnish or contains much lampblack. This effect is increased if Frankfurter black or powdered charcoal is mixed with the color, and the stone is kept very wet.

(2) The partial preparation is produced more quickly and made more durable if the water contains gum or gummy stuffs.

(3) The operation is still quicker if a weak etching fluid is used. A stronger fluid would make the preparation a complete one, but would also injure the good spots. Then again one must remember that the second etching produces the roughness discussed already.

(4) Grinding with sand, pumice, and other grinding materials also produces partial preparation, which is transformed easily into complete preparation by applying gum. Here, however, the circumstance is noteworthy that a plate that has been blemished by rubbing can be made to do the reverse, namely, to take color, by means of light grinding with water. Assume, for instance, that a plate designed and prepared in relief style has been spoiled by handling so that the design refuses to take color. It is necessary merely to rub it all over with water and fine sand or to clean it with oil of turpentine so that all printing-color is removed from the surface. Then place it in a receptacle containing a great deal of very clean water. If it is ground delicately then with a very clean pumice stone, without destroying the traces of the fatty material that has soaked in, it can be brought to take color again as well as ever. Take a little of the before-mentioned acid-proof ink, smear it on the color-stone, and apply a clean linen or cotton rag. Wipe the stone that is lying in the water very gently with this rag, and the color will fix itself bit by bit on all parts of the design, even if the entire relief produced by the etching should have been ground away. It is necessary only that the fat shall have soaked in sufficiently; and this usually is produced soon enough by the printing. After the plate has accepted color completely, it is to be completely prepared by light etching and with gum, and then it will take the color properly from the ink-roller.

If this experiment is to succeed, it is to be noted that in grinding there must be no trace of fat on the stone or the pumice, because the rubbing during grinding might transfer this greasiness to those parts of the stone that are to remain white. Care must be taken, also, not to press too hard in applying the etching color, because the places that have been cleansed of all gum by the water, and thus are inclined to accept color, will smut easily. Finally, the stone must not be permitted to dry before it is fully prepared again by etching and gum coating, for it might easily become entirely smutted and useless.