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Media Kerja Cetak Dalam. Pertemuan 10. Bina Nusantara University. Once the edges and the back of the plate are protected, it is immersed in a basin containing some diluted acid.
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Media Kerja Cetak Dalam Pertemuan 10
Once the edges and the back of the plate are protected, it is immersed in a basin containing some diluted acid. The most commonly used types of acid are nitric acid and perchloric acid. Nitric acid is almost always used on zinc plates, and perchloric acid on brass and copper. During the "biting", that is the acid's corrosive action, the acid creates small bubbles that settle on the carved drawing. As they form, the artist removes them using the feather of an aquatic bird ( which are the most resistant type), in order to obtain a regular line. Moreover, during the chemical reaction perchloric acid deposits in the furrows a rust-coloured pulp which impedes the biting; so that plates are often washed or held upside down so that the pulp falls into the basin. Using a different concentration of acid and varying the biting times different kinds of lines and results can be achieved. Types of biting: 1) simple - after one immersion in the acid, the lines have all the same strength: the shades and color gradations are created by the more or less dense network of lines. 2) layered - after successive multiple immersions. The engraver immerses the plate in the acid a first time, then covers with a protective wax the lines that must be thinner and lighter in the print. Then the plate is immersed again to obtain thicker lines and the procedure is repeated as many times as required to obtain wider and deeper lines. In the print the sharp edges due to the different moment of biting will be clearly visible. 3) addition - when the darker lines are the first to be engraved and thinner and lighter lines are added step by step through a series of immersions. This method creates not only sharp lines, but also areas of soft shades and nuances, because the artist can change any part of his work until the moment of biting.
The plate is inked before the printing of each sheet of paper. The printing process is done with a hand press on a movable plane passing between two metal rollers.
Between the cylinders pass : a) the plane b) the inked plate c) the wet sheet of paper attached to the plate d) d) a blotter to absorb the water from the paper squeezed out by the cylinders. By pulling a lever, the entire rolling process is set into motion.
