the infernal method

The "infernal method" of printing that Blake discusses here was his way of being able to print both his words and illustrations on the same printing plate. By conventional means, this would not have been possible, since text was generally set in letterpress (each letter on its own block, like a rubber stamp, and placed together) and illustrations through intaglio engraving or etching (instead of raised surfaces holding ink, like letterpress or woodblocks or rubber stamps, the grooves made by the engraver/etcher are what holds the ink: flat surfaces print white), which are both printed through different processes. In traditional etching, importantly, the printer begins by coating the whole surface of the plate with an acid resistant ground, then drawing through that ground with a pointed stylus. When placed in the acid, the lines drawn are bitten into the plate, and later, are the lines that show up after the plate is run through the printing press.

The infernal method mixes all of this up. Blake instead painted and drew his illustrations and words onto the copperplate with a stop out varnish, resistant to acid. When placed in the acid bath, the blank sections would be eaten away, leaving the words and pictures raised, like in a relief print. This is even more infernally complicated when you also keep in mind that Blake had to write and draw in reverse, since the printing process switches everything around.

Keeping this background in mind, Blake discusses this process of printing as the way in which "the notion that man has a body distinct from his soul" can be "expunged." Not by any traditional means can this occur, but through the innovative and infernal means of his printing method, which combines different printmaking practices, as well as unifying the written word and its illustration. Further, the means of revealing this essential marriage of body and soul within man relies on "melting apparent surfaces away, and displaying the infinite which was hid," just as the process of infernal printing does. The "apparent surfaces" of separateness preached by heaven must be corroded by acids "which in Hell are salutary and medicinal" though percieved as "infernal" by angels, much as the vision of hell alters depending on the viewer. Similarly, the traditions of printmaking which keep word and image separate are corroded away. It is only through the action of innovation and the violence of the acid bath that man can unify himself and Blake can unify his art, and the energy of hell is required for both.

(see mentions of the infernal method here, here, and here, the place that I learned about it.