Lithography
The term lithography comes from the
Greek words for stone and writing.
The
process of lithography was invented in the 1790’s
by Aloys Senefelder in Munich, Germany. Senefelder, an impoverished
writer, was trying to develop an inexpensive way to publish
his plays. After accidentally discovering the effects of
greasy ink on limestone, he patented the process and spent
the rest of his life perfecting it. Today, lithography is
used for the commercial printing of magazines and posters
as well as fine art works.
The principle of lithography is that grease
and water repel each other. In lithography, the artist draws
on a stone or aluminum plate with a greasy crayon or with
tusche, a liquid grease. Lithographic stones can be used
over again by resurfacing or graining the stone with carborundum
grit. Plates can also be made light sensitive and used with
a photographic image. The drawing is processed with a slightly
acidic etch, consisting of gum arabic mixed with drops of
nitric or phosphoric acid. The drawing becomes hardened
and the surface of the stone becomes desensitized to grease.
The etching process leaves a gum Arabic mask around the
drawing. The drawing is washed out with lithotine. The gum
Arabic does not wash away because it is water-soluble. Ink
is then rubbed into the drawing, and the gum is washed away.
The stone or plate is kept moist with a wet sponge while
the printer rolls up with an inky roller. The ink, being
greasy, attaches itself to the drawing and not the clear
areas, which are wet and repel the grease.
When
the stone or plate is rolled up with ink, the printer lays
a sheet of paper over the stone. A thin sheet of plastic
called a tympan goes on top. A bar coated with leather or
Teflon is pulled down onto the tympan with enormous pressure.
When the printer turns a crank, the bed of the press moves,
the bar slides over the tympan, and the image gets transferred
to the paper.
Artists were attracted to lithography for
it’s resemblance to charcoal drawing. Honoré
Daumier, Henri de Toulouse Lautrec, Winslow Homer, Pablo
Picasso and Jasper Johns are among the many artists who
have made lithographs.
