In wood-engravings, on the contrary, the ink, when applied, is taken up by the parts left prominent, and never penetrates into the engraved lines; so that, in the impressions taken on paper, the portions of the wood less prominent communicate the shades, the portions cut away, on the block, remain colorless and blank.
Thus the same process, pursued on the metallic plate, and on the wood-block, produces effects diametrically opposite, and to produce the same effects from the two materials converse processes must be pursued.
Thus we will engrave the word
on a plate of metal, and on a block of wood, and let these two engravings be perfect fac-similies, line for line alike, in form, length, width and depth; then, the impression taken from the engraved plate of metal, being derived from the depressed lines, filled with ink, into which the paper is forced by the action of the press, will present the appearance shown above.
But, the impression taken from the engraved block of wood, being derived from the elevated portions of the block, covered with ink, upon which the paper is impinged by the action of the press, will give the appearance presented below.
Observe, therefore, that as on the two engravings, the same work produces results exactly the reverse, one of the other; so to produce the same effect from each of the two engravings, we must have recourse to two different processes.
The former of the above two cuts, is the effect produced on paper from a metallic plate, into the surface of which the lines producing the shades are engraved or cut in.
The same effects precisely may be produced on paper from a wood-block; but, in order to produce it, all the portions of the wood-block, which now give solid black upon the paper, must be cut out of the wood; leaving the lines, which now give white on the paper, prominent, so as to receive the ink and make their impression on the surface to be printed.