Zincography

As Zinkografie, Zinkhochätzung or Chemigrafie is called a HW Eberhard invented in 1804 in Magdeburg process using zinc plates instead of expensive, heavy lithographic stones. First, the zinc plate was treated as a lithographic stone and used in flat printing process in the lithographic press. From 1850, the proceedings in the Barbizon school of Charles Emile Jacque and Karl Bodmer was used for illustrations in books and magazines and developed. You described this art as Gravures en relief or procédé Compte.

Method

The transfer printing is effected using a special transfer sheet to the zinc plate having a soluble layer that adheres together with the ink to the metal. The printing image is reinforced by the arabic coating with a solution of rubber and dilute color. The dried sheet is then dusted with a fine, derived from a mixture of wax, rosin and asphalt powder that you can begin to melt under slight heat, while larger picture vacancies and the whole back side is coated with a solution of shellac and alcohol.

Etching placing the plate in a flat, poured out with pitch wooden vessel, which is about 2 cm high filled with a mixture of 40 parts of rain water and 1 part pure nitric acid. The plate is rinsed and dried in about 2 minutes in pure water. The resin powder is again melted in such a way that it easily flows down to the color of the markings on their strokes. The process engraver now wears a color mixture of book and stone printing ink which is added a little resin and wax on with a leather roller. Thereafter, the plate is placed back into the caustic water, and repeated up to the etching process under reinforcement, optionally regeneration of etchant six times.

After the sixth etching the paint is washed off with turpentine and a sharp brush, put the plate in a hot potassium carbonate solution and dried. Larger areas which should appear white after printing, chiseled or sawed what already done a Reinätzung.

Chloric acid used for etching results in nice, shiny surfaces and clean, sharp lines. Although it has been possible to bring the zinkografischen etchings to a high quality standard, they can replace the woodcut only where it is less important than artistic completion of production on rapidity of formation of illustrations or accurate facsimile. A further development of Zinkografie is called Elektrochemitypie.

Chemigrafie

The modern Zinkografie is called Chemigrafie. Until about 1956, this procedure was carried out as follows:

First on the reproduction photographers a glass plate was thoroughly cleaned and provided with an adhesive base. This primer consisted of a solution of washing or surgical spirit with an adhesive. The mixture was poured onto the glass plate, and dried. Mostly, several plates were prepared as stock for a day's work.

Then the photographer coated glass plate with a liquid photosensitive Kollodiumpräparat and put the wet photographic plate in a cassette, which was suspended in the process camera. The approximately 10-minute exposure was carried out with 4 carbon arc lamps.

After development, fixing, washing and drying of the plate, a photographic negative of the printed image was present. Meanwhile, a 1.5 mm thick zinc plate was degreased in appropriate size and provided with a light -sensitive layer. Their light sensitivity was so low that the process engraver could work at yellow light. In a printing frame, the photographic negative was placed with the coated side onto the light- sensitive plate of zinc and pressed under vacuum. The exposure was also carried out with carbon arc light. In this case, the exposed image areas become hardened, while the unexposed areas were rinsed with water, so that a positive pressure image appeared on the zinc plate. By heating the plate to about 300 degrees Celsius, the pressure image was made acid resistant.

The first etching was carried out in very dilute nitric acid in a Ätzschale and contributed about 0.1 mm from the zinc plate. Until the 80s mechanical etching machines were used. The bathroom contained therein (emulsion) of nitric acid and flank protection agent was thrown over paddle wheels on the closed lid, rotating zinc plate. Not printing ends games had about 0.5 mm deep. Larger non-printing parts are put additional deeper into the milling. ( This saved too early saturation of the acid bath ) Each zinc plate consisted of several loosely conjoined subjects, which were then separated with a meat scissors. Depending on the amount of etched-out metal, the acid bath was saturated sooner or later and had to be drained. In earlier times simply diluted into drains, the latest in the 80s it was collected in separate containers in the engravers, then neutralized with sodium hydroxide solution and poured down the drain.

Today the chemigraphy for the production of embossing plates for blind embossing or embossed leathers still plays a role. To magnesium cliches are used.

After completion of the cliché, a preprint was prepared for review.

Known Chemigrafen

• Helmut Lohner
• Karl Hodina