There are many ways for the printmaker
to control the acid's effects. Most typically, the surface of the
plate is covered in a hard, waxy ground that resists acid. The printmaker
then scratches through the ground with a sharp point, exposing lines
of metal that are attacked by the acid. Once the drawing in the
ground is finished, the plate is submerged in acid for a period
of time; longer submersion means that deeper lines are etched. The
ground may be removed, or the artist may continue drawing in it,
etching it again in acid to deepen existing lines while adding new
lines. The ground may also be reapplied to protect existing lines
while adding new ones. The ground may be removed and the plate printed
to see its current printing state, to be followed by more work (or
other techniques, such as aquatint, drypoint, or engraving); thus,
many of Rembrandt's etchings exist in several distinct forms, with
the final, "accepted" version apparently preceded by many
artist's proofs.
A "soft" ground may also
be used--a ground that is sensitive to pressure. The soft ground
is applied to the plate, and the artist removes it by putting paper
on top and drawing on the paper. The varying pressure of the pencil
on the paper lifts the soft ground in a likewise varying amount,
in a particulate way--rather than removing the ground, its density
is decreased, allowing more or less acid through. The effect is
much like that of particulate mediums like chalk, charcoal, or pencil:
the image burned into the plate is composed of greater and lesser
densities of minuscule pitting, rather than sharp, continuous lines.
Minor variations involve putting a soft ground on a plate along
with some textured surface (such as fabric or crumpled plastic wrap
or paper), and then running the combination through a press, transferring
the texture to the plate.
Aquatint is a variation in which
particulate resin is evenly distributed on the plate, then heated
to form a screen ground of uniform but less than perfect density.
After etching, the result is a uniformly roughened (i.e., darkened)
plate that may then be drawn on by smoothing it, creating the image
from dark-to-light rather than the reverse.
Printing the plate is done by covering
the surface with ink, then rubbing the ink off the surface with
tarlatan cloth or newsprint, leaving ink in the roughened areas
and lines. Damp paper is placed on the plate, and both are run through
a printing press; the pressure forces the paper into contact with
the ink, transferring the image (c.f., chine-coll). Unfortunately,
the pressure also degrades the image in the plate subtly, smoothing
the roughened areas and closing the lines; a copper plate is good
for, at most, a few hundred printings of a strongly etched imaged
before the degradation is considered too great by the artist. At
that point, the artist can manually restore the plate by re-etching
it, essentially putting ground back on and retracing her lines;
alternately, plates can be electro-plated before printing with a
harder metal to preserve the surface. Zinc is also used, because
as a softer metal, etching times are shorter; however, that softness
also leads to faster degradation of the image in the press.
Faux-bite is common in etching,
and is the effect of minuscule amounts of acid leaking through the
ground to create minor pitting and burning on the surface. This
incidental roughening may be removed by smoothing and polishing
the surface, but artists often leave faux-bite, or deliberately
court it by handling the plate roughly, because it's viewed as a
desirable mark of the process.
Artists: Pablo Picasso,
James Ensor, Paul Klee, Edward Hopper, KŠthe Kollwitz, Otto
Dix, Henri Matisse, Giorgio Marandi, Cy Twornbly, Brice Marden,
Jim Dine, and Lucian Freud.