Etching
Etching describes a graphic gravure printing process in artistic printmaking , a possible form of etching .
The pressure plate
The etchable printing plate is covered on both sides with an acid-resistant layer - the etching base or masking lacquer , a mixture of wax, mastic and asphalt. The drawing is mirror-inverted on this plate and lightly scratched into this acid-resistant layer with an eraser, roulette or moulette . This is followed by an acid bath ( nitric acid or iron (III) chloride is common ), in which the acid etches the metal at the scratched areas. In the beginning of the etching, a mixture of vinegar , table salt , copper sulfate and ammonia ( ammonium chloride ) was used as "etching water" .
The aquatint technique is used to color surfaces . Scattered rosin grains are melted by heating and create an irregular, rough surface after the etching process.
The etching
Depending on the duration of the acid exposure, the lines become stronger or weaker. If individual areas are to appear stronger, the remaining areas are also covered with the acid-resistant layer and the plate is placed back in the acid bath. A single printing plate can thus have a number of etching operations. A gradation from the lightest gray to the deepest black is achieved in the print. The decisive step in the artistic development of the etching lay in the invention of the gradual etching.
The pressure
After removing the etching base with turpentine, the plate is colored with the printing ink and cleaned of color with a spatula, linen gauze and finally by wiping with the ball of the hand so that only the lower-lying, printing plate parts are color-bearing. The printing ink is released back onto the printing paper during the subsequent printing. A dampened sheet of gravure paper (hand-made paper ) is pulled through with a pressure felt for better pressure transfer and two iron plates under high pressure between two rollers. The paper is pressed into the indentations and absorbs the color.
The variants
The process of deepening metal plates provided with an etched base with acid in the unprotected areas has traditionally been used in the arts of gravure printing, in addition to surface etching ( aquatint ), line etching and soft ground etching ( vernis mou ) as further expressive options . Since metal plates, appropriately prepared, can also be etched in stages , the variants can be combined on one plate.
literature
- Wolfgang Autenrieth: New and old techniques of etching and the fine printing process. From “witch's meal and dragon's blood” to the photopolymer layer. Tips, tricks, recipes and instructions and recipes from five centuries. (An alchemical workshop book for erasers. Tips and tricks from practice). Version 6.3 from October 9, 2010. Autenrieth, Krauchenwies 2010, ISBN 978-3-00-035619-3 (→ excerpts online) .
- Walter Koschatzky : The art of graphics. Technology, history, masterpieces (= dtv 2868). Unabridged edition in the text, 8th edition. Deutscher Taschenbuch-Verlag, Munich 1985, ISBN 3-423-02868-8 .
- Volker Steinbacher : Etching workshop - engraving, printing, coloring. English, Wiesbaden 2006, ISBN 3-8241-1337-6 .