PREPARING AND ETCHING THE PLATE
A metal plate (zinc pictured) is cut to size and the edges are beveled, filed and polished. The surface of the plate is then degreased and coated with a thin layer of wax ground.
A fine etching needle is used to draw directly onto the plate. This removes the wax coating and exposes the metal in certain areas. Once the image has been completed, an acid-resistant varnish is painted onto any weak or scraped areas of the ground that should not be exposed. The reverse side and edges of the plate are also protected with an acid-resist.
The plate is immersed in an acid bath which bites into the exposed areas, and etches the lines and marks made by the needle. The longer the metal is in the acid the deeper it bites into the surface, creating a recess that will hold more ink and print thicker line. The plate is normally bitten in stages so sections can be painted with an acid-resistant varnish and create different qualities of line.
Once the lines have etched to the right depth, the plate is removed from the acid bath and rinsed. The wax ground and varnish are cleaned off and the first proof of the plate can now be printed.