14 October 2010 § Leave a Comment
category: manual intaglio printing
Originally and for a long time only copper plates were used for etching. In the 19th century zinc and steal sometimes took the place of copper. Already in the late 18th century zinc etching became known. It is uncertain who first invented that zinc was fittable for etching techniques. Probably the use of zinc came forth of the search for less expensive production processes. Zinc is significantly cheaper than copper and in combination with a higher account of book production for a printer the use of zinc in stead of copper can be cost saving.
Nevertheless etching in zinc brings some differences according to etching in copper. Not only zinc is cheaper then copper, but also considerably softer and therefore not applicable for aquatint or dry point. Because of this softness a maximum of about 200 prints can be made of one zinc plate, which is a disadvantage for a high impression. This objection was taken away when the technique of electro-metallurgy was discovered, through which the zinc plate can be covered with a copper coating. Zinc also has a rougher structure and therefore it is more difficult with zinc then with copper to clear the plate from redundant ink before printing.
The etching procedure of a zinc plate is basically the same as the procedure of a copper plate (see: the lemma about etching). Generally it can be said that zinc etching gives an more irregular line than copper etching: the softness of the zinc gives way for the acid to bite more freely into the metal and the chemical reaction between zinc and the etching water produces more gas. That is why the bite of the etching water has to be slower and another composition is necessary than used with copper. Basically the etching water contains one piece nitric acid and ten pieces water, but, for example, sulphiric acid in a mixture with nitric acid can also be used. The difference between ferric chloride, almost only used with etching in copper, and nitric acid is that the latter not only bites in width, but also in depth. That is why the lines in the ground of a zinc plate must stand further from each other than lines on a copper plate to be bitten in ferric chloride, otherwise the ground between two or more lines on the zinc plate would be totally bitten away. Every etcher has his own recipe of etching water, which depands on his objectives and the print he wants to produce. Etching in zinc is especially applicable for rough drawings without many fine details such as shading. [John Tholen]
Hamerton, P. Etching & etchers, London 1868
Hendriks, A. Etsen. Handleiding voor het etsen op koper en zink, Alkmaar 1944
Huffel, N. van Encyclopedisch handboek der grafische werkwijzen, Utrecht 1926
Linden, F. van der De grafische technieken, De Bilt 1980