AQUATINT: An intaglio process of etching on copper or steel plates to which acid-resistant granules have first been evenly adhered. The etching ground in aquatints is much more porous than in stipple engravings. Aquatints produce a soft half-tone effect. One of the most famous uses of this technique was by Havell for John J. Audubon's Birds of America.
CHROMOLITHOGRAPHY OR COLOR-LITHOGRAPHY: Color printing using lithographic methods. A lithographic stone is needed for each color. This results in a somewhat greasy, shiny appearance. The process requires considerable skill (and expense) to do well because of the multiple printing.
COPPER-PLATE ENGRAVING: Intaglio engraving on copper. Before the end of the 15th century, copper engraved plates came into use and had, by the end of the 16th century, essentially changed bookmaking all over Europe - replacing the woodcut. The drawing is transferred to a copper plate in reverse. The lines are cut away with a burin (the deeper the cut, the more ink it used and the darker the eventual printed line).The plate is then inked and the image taken from it.
ETCHING: Line-engraving. Lines or flicks are incised into a copper or steel plate by the use of a burin or 'graver', a steel instrument with a lozenge-sectioned, pointed end, and a mushroom-shaped wooded handle. This is pushed forward on the plate, forcing out a shaving of copper in its path. Depending on the angle at which the burin is held, the line can vary in width.
INTAGLIO PROCESS: Printmaking methods where the action of a roller press forces the paper into lines or marks sunk beneath the surface of a metal plate, squeezing the ink from them so that it stands out in slight relief from the paper. Etching, engraving and mezzotint are intaglio processes.
STEEL-PLATE ENGRAVING: Same technique as copper-plate engraving. Became popular in the mid 19th century (more durable than copper).
STIPPLE ENGRAVING: An etching rather than engraving technique. Acid, instead of a tool, is used to cut into the copper plate. The plate is first covered with a substance impervious to acid, such as varnish. Etching needles and punches transfer the design, in the form of small dots, through the etching ground to the copper beneath. When the acid is applied it eats through the copper where the dots have been punched, leaving intact only the areas covered with the ground. A very delicate and varied tone is produced. Invented by Bartolozzi in England, but perfected in France by artists such as Langlois, Redouté, Bessa & Prévost.
STONE-LITHOGRAPHY: Invented by Alois Senefelder in 1796. A smooth stone (such as limestone) receives the design in pen & greasy ink/crayon. The stone is then wetted, with the greasy inked areas rejecting the moisture. Ink is then passed over the stone, and the area where the greasy ink/crayon was used accepts it. Paper is pressed directly onto the stone. John Gould's Birds are examples of stone-lithography at its finest!
WOODCUT: The earliest method of printing, developed around 1400. The image is drawn on a wood block. The space between the lines is cut away, so that the lines receive the ink. The image is drawn in reverse, so that when the inked block is pressed to a sheet of paper, the print appears in the intended direction.
WOOD-ENGRAVING: A refinement of the wood-cut, in which the engraver uses a burin, the fine steel cutting tool of copper engravers, to obtain a multitude of fine lines that result in subtle gradations of gray tones. Thomas Bewick (1752-1828) is generally considered to be the inventor of wood engraving.
DEL Delineavit or delineaverunt - he/she drew. Refers to the artist. Usually on bottom left-hand side - after the name.
DIR Direxit or direxerunt - the person(s) sho supervised the engraving. Usually on bottom left-hand side.
EXC Excudit or excuderunt - engraved by. Always follows a name.
FE or FEC Fecit or fecerunt - made by. Less common than Del.
IMP Impressit or impresserunt - printed by. Usually below title of plate.
LITH or LIT refers to lithographer.
PINX Pinxit or pinxerunt - painted by. A less common alternative to del. Sometimes denotes the hand-colorist.
SC or SCULP Sculpsit or sculpserunt - engraved by. Usually on bottom right-hand side following engraver's name.