HALF-TONE PROCESS BLOCKS.
The subject, whether it is a drawing, engraving, painting, or a photo print, must in each case be photographed to obtain upon the negative the texture which is the means of producing the gradations of light and dark we find in the finished block. The theory is simple enough, but the practice is extremely difficult, and one requiring great skill and care. A glass screen having cross lines ruled upon it, with perfect mechanical regularity (about seventy lines to the inch for large work, up to two hundred lines to the inch for very fine half-tone blocks, as may be best suited to the subject in hand). The screen is fixed in the camera between the lens and the negative to be exposed. The fine black lines of the screen are reproduced upon the negative as white lines, breaking up the picture into a series of minute square dots, of varying size according to the light and shade of the original picture. A photo-transfer is then taken as previously explained. (In Hentschel’s process the secret of the prepared transfer paper is in the possession of Mr. Hentschel solely.) After being transferred to the zinc, and manipulated with certain chemicals, the plate is gradually etched until a sufficient depth has been obtained. It is then trimmed and mounted type height ready for the printer.
Pen and Ink Drawing, reproduced by process block.
Original size.
Pen and Ink Drawing,
reproduced by process block in three sizes.