List of therms» Lithographic tusche

img_slownik_tusche.jpg

Lithographic tusche is available in three forms: stick, paste, and liquid. Although the three are compounded of basically similar materials, each has subtly different characteristics. The stick and paste tusches are more flexible in that they may be used with water, turpentine, or a petroleum solvent.

In general, tusche mixed with water flows more freely and dries more slowly. Tusche mixed with other solvents tends toward greater viscosity and penetrates more deeply into the stone. The image so produced, being more deeply seated, is richer and more resistant to etching than the image made with water tusche. As a result, solvent-tusche images have a tendency to print darker than they appear in the drawing. Tusche, when diluted with either water or solvent, is extremely sensitive to the slightest variations in use. Careless handling leads to uncertain and unpredictable results. In the hands of an experienced lithographer, however, tusche is a fine and versatile material with an all-butinfinite range of uses.

Before a liquid tusche is used, the bottle should be well shaken to ensure an even suspension of the liquid. Water tusche in any form should be diluted only with distilled water. Tap water contains minerals that may affect either the stability of the tusche, causing it to separate, or its greasiness. Should lime be present in the water used to dilute tusche, the greasiness of the mixture will be reduced, leading to a pale and unpredictable image.

Stick or paste tusches also may be mixed with distilled water. The best way to prepare stick tusche is to rub it vigorously against a dish or saucer. Heating the saucer first by holding it against an incandescent light bulb for a few moments will cause the tusche to soften and make the process easier. Water is then added a few drops at a time, and the tusche is worked up with the fingers or a brush.

Paste tusche can be mixed easily with water, using a brush or a palette knife. There is no objection to adding a few drops of water directly to the tusche in the can. If this is done, however, the same can should not be used later for mixing tusche with other solvents. One can of tusche should be used for water mixtures and a second can for solvent tusche.