PREPARING ZINC PLATES ON THE PRINTER’S PRESS.
A wood-cut gives the outrunners of the finest portions in a plane which runs downward; an etching, on the contrary, shows the whole engraving in one plane. According to this the outrunners (the borders) often print somewhat hard, unless care is taken to alleviate this fault. This will be easy to the experienced workman. {103}
Starting from the fact that a zinc plate is easily bent, place something under the back of the heavy portions in mounting, and when nailing drive the nails tight in the white lights and on the edges; thus the borders are deepened, and print softer.
In this manner an experienced and practised hand can produce effects impossible in any other way.
For printing on rotary machines, galvanos are used in many places. But a zinc plate may be excellently fastened in the following manner:
Clean the back well and solder the back with soft solder, as is customary in galvanic backing. Then attach it lightly to its place on the wooden or metal block, hammer or roll in the plate without paying special attention to the zinc plate, dry the matrix, and lift it from the form. After preparing for casting take the zinc plate from the wooden block, bend it while hot, put it back into its position in the matrix, cover the edges with tissue paper and paste, dry the edges with an iron, place into the casting apparatus and cast as usual. In this manner the zinc plate (metal, cast from a matrix) is in place at exactly the height of the type and will print excellently. (The face is to be slightly oiled before fastening in the matrix, to prevent any sticking of the lead.)
As a cover for the printing cylinder, I have always found paper most serviceable, although covers of English leather are also advantageous, especially for large editions. I should not recommend felt.
The rollers for printing zinc plates should be held with somewhat stronger tension than for printing of wood-engravings.
As a method of preparing, I recommend the gradating of the lights and shades, known to every intelligent machinist. Wherever possible, highly calendered paper should be used, as it gives the best results.