The Intaglio Processes for Audubon’s Birds of America

Notes on the intaglio processes of the most expensive book on birds available for sale in the world today.

The Audubon prints in “The Birds of America” were all made from copper plates utilizing four of the so called “intaglio” processes, engraving, etching, aquatint, and drypoint.   Intaglio processes are those by which the design to printed is cut down into the surface of the plate, and will yield an impression in relief.

The design is rendered upon the plate either with a tool or by the action of an acid eating into the copper plate through an acid resistant coating called a “ground.”

The design consists of incised lines, mottled areas used to create “half tones”, and combinations of the two.  After the incised lines or mottled areas have been created, they are filled with a stiff ink and the surface of the plate is wiped clean.  A sheet of damp paper is laid over the plate, and upon being subjected to a great amount of pressure by a press, the paper is forced into the lines and mottled areas, attracting the ink and resulting in a print.  The embossed ridge on the paper which is made be the roller as it passes over the edges of the plate distinguishes hand printed works from other large scale commercial processes.  This ridge is called the platemark.

Each of the four intaglio processes presents its own characteristics.

Engraving is that process where a crisp, sharp line is “slivered” out of the plate by hand with the use of a special tool called a burin.  The burin has an exceedingly sharp triangular tip that will dig into the copper and liver out a line when pushed by the hand.  The resstance of the copper to the tool handicaps extreme flexibility of design.

In etching, the copper plate is cleaned and polished and the surface coated with a wax, while the sides and back of the plate are protected with an acid resistant varnish.  With the use of a steel needle the design is created on the plate by cutting through the wax surface, and the plate is then immersed in a bath of acid and the exposed copper is eaten away, thus leaving an incised line on the plate.

Aquatint, like etching, employs acid to eat the design into the metal.  It differs from etching in that it yields fine shadings in the degree of darkness in the non-lined areas.  In the aquatint process the design is produced by sprinkling the plate with fine dust of a resinous substance (the ground) and affixing the dust particles to the plate with heat.

In this process the depth of the design in the plate is controlled by the extent to which the acid is allowed to bite during a series of aced baths.  The deeper the acid eats, the darker is the resulting area in the print.  Arias that are to print black are given full exposure to the acid, which eats a pit around each of the original dust particles.  Areas that are to print gray are covered to protect them from the acid after one or two immersions. Areas that are to be white in the print are kept permanently covered with an acid-resistant varnish.

A drypoint is that linear design on the copper that has been obtained by the strength of the artist’s stroke with a steel or a diamond needle.  Just as in engraving, the line is controlled by hand.

The softness of the drypoint lines is of particular note.  Just as a plow throws up a ridge of earth beside the furrow , the drypoint instrument leaves a ridge of metal called the “burr” which softens the incised line.

Robert Havell, engraver of “the Birds of America,” employed all these techniques, with utilization of engraving and aquatint being predominant.  Havell’s great control of the buring and his economical use of aquatint producing half tones, to obtain the effects of dark and light (chiaroscuro) are his trademarks of success.  The manner of the flowing water color washes over the aquatint on the final print adds to the illusion of gradated tone.

Another technique that Havell uses is that of “feathering”, a process by which he allowed the acid to bite a granular surface upon the bare copper plate without using and acid-resistant material (ground).  This results in soft gradations.

Some of the small plates are etchings combined with some aquatint; and the larger plates, several with an area of over five square feet, are mostly engravings combined with aquatint and heightened with the use of drypoint and etchings in many cases.

The engraved line that is remarkably pure, the aquatint which is expertly merged with line, and the use of etching and drypoint to create richness an depth are all proof of the skill Havell possessed.  —Robert Bornhuetter – 1966 as published in a soft-cover print book produced by the Louisiana State Museum and Friends of the Cabildo entitled Audubon in Louisiana.