Printing
Techniques can be identified through magnified examination.
Relief printing utilizes a block of wood, linoleum or stone where the image
is cut away from the lines. Ink is placed on the surface of the cut. Early
examples are Japanese block prints and the works of Albrecht Dürer
Intaglio is an engraved or etched image. Ink is held in the recessed areas
of the plat and wiped clean on the surface. Using pressure the paper is forced
down onto the plate and the ink is transferred. Peripheral plate marks from
pressure indicate intaglio printing. Etchings have a resist or waxy substance
on the surface and lines are carved out of wax. The result is a softer edge
on the inked line because the ink spreads and diffuses away from the line.
Copperplates, zinc or steel are used for engraving. Designs are carved with
a tool (burin) or etched with acid, was inked and surface carefully wiped
so that the ink remained only in the incised areas and was able to be transferred
to paper under the concentrated pressure of a cylinder press. Engraving leaves
crisp clean lines.
Lithography, or drawing on stone, uses water, ink and oil to produce a print.
This is the first printing process allowing mass produced images. Toulouse
Lautrec sanded Bavarian stone and applied his images with grease. Dampening
the stone's surface forces water away from the oily substance that forms the
image. Ink is attracted to the oily area and is repelled by the water in the
ungreased areas. The image is then transferred to paper on a press. Each color
require a separate stone. Under microscopic enlargement you can see a sandy
pattern.
Seriography is a variation of stencil printing. A fine screen stretched
on a wood frame carries a negative image of what is to be printed. The process
leaves a thick layer of ink dot pattern and texture from high pressure application.
Photo-mechanical printing produces a uniform dot pattern.