Lithography,
invented in Germany in 1798 and now considered the first and most
important method of planographic printing (printing from a flat
surface, or plane), is based on the chemical principles that oil
and water do not mix but will attract like substances, and that
both will adhere to a porous ground, such as a stone. The process
came into widespread use in the 1820s as commercial printers and
artists realized that images could be drawn as easily on stone
as on paper, and that the stones could be reused. All methods
of drawing could be used on the stone, including pen-and-ink,
chalk, or crayon, and by about 1830 a watercolor-like wash, applied
with a brush, was used to provide tints known as lithotints.
Only after the development of cheaper printing methods such as
wood engraving and lithography did it become possible to print
inexpensive illustrated medical textbooks. Although lithographs
could be produced more easily, and generally more cheaply, than
relief or intaglio illustrations, color was still expensive since
it had to be applied by hand and so was used only for relatively
upscale colored scientific and medical books.
During the
nineteenth century, lithographers perfected the art of printing
in color by using multiple stones to achieve very complex colored
images through a process known as chromolithography. Cheap color
printing was then available for the first time in the history
of printing. While the most pervasive use of chromolithography
was in advertising, it was also used extensively for making popular
prints as well as for scientific
and medical illustrations.
