Anastatic printing

(From Anastasis, resuscitation, raising up again)

This process for producing copies of manuscript, or printed documents, or engravings, that can with difficulty be detecte from the originals, was invented by M. Baldermus, at Erfurt about 1841. It was soon after made public and Faraday explained the process at the Royal Institution, April 25, 1845. It has since transpired that a similar process had been employed in England some time before M. Baldermus’s invention was made known. The invention was improved and extended by Strickland and Delamotte in 1848.

The process is analgous to lithography, but a zinc plate is employed instead of a stone. A printed page, an engraving, or a blank note may be exactly copied by this invention. Moisten the printed paper with dilute phosphoric acid, lay it downwards on a clean sheet of zinc, and put it into a press for a short time. The acid of the unprinted parts etches the zinc beneath, while the printed part also sets off on the zinc, and thus produces a reverse copy of the printing. Wash the plate with an acid solution of gum, and it will be ready for use. The plate may now be treated as the stone in lithographic printing; first damped and then rolled. The affinity of the ink to the letters already “set off” on the plate, and the repulsion of the other parts of the plate, cause the lines of the device to take the ink, but the other parts remain clean; the printing then follows.—See “A brief Description of the Art of Anastatic Printing, with illustrative specimens and full directions.” By S. H. Cowell. Ipswich: 1868.