Drawing, etching, and the printed line
Drawing, in the plain sense, means making marks on a surface by pressing a tool into it or dragging a tool across it. A tool is part of the definition. Without one, the same activity would be filed under some other name. Graphical drawing is drawing guided by an instrument: a straight edge, a compass, a burin, later a plotter. The hand is still in it. The instrument keeps the mark honest.
A drawing can be a study of a particular face. Around 1510 Leonardo da Vinci made a portrait in sanguine, a red chalk, on paper. It may be a picture of the artist himself. The sitter is not the point. A drawing of that kind is already a complete graphic: one tool, one colour of mark, a sheet, and a person a viewer can recognise five centuries later.
Multiplying the picture
A drawing exists in one copy until someone prints it. Woodblock printing that includes images is first seen in China after paper was invented, about A.D. 105. In the West the main techniques have been woodcut, engraving, and etching, but there are many others. Each one answers the same practical question. How do you make the picture more than once, without asking the artist to draw it again from scratch?
Etching is an intaglio method. The image is incised into the surface of a metal plate using an acid. The acid eats the metal, leaving roughened areas or, if the bare metal is only a thin line, burning that line into the plate. Ink sits in the bites. Paper takes it up. The use of the process in printmaking is believed to have been invented by Daniel Hopfer of Augsburg, who lived from about 1470 to 1536 and decorated armour this way before the idea moved onto copper plates for paper.
The same bite of acid turned out to be useful far from the print shop. Etching is also used in the manufacture of printed circuit boards and of semiconductor devices. A picture of a circuit, reduced and repeated, becomes the circuit. That is a graphic with consequences you can measure with a meter.
Line art
Line art is a loose term. It is used for any image made of distinct straight and curved lines placed against a background, usually a plain one, without gradations of shade or of hue standing in for a two-dimensional or a three-dimensional object. Line art is usually monochrome, though the lines themselves may be of different colours. A wiring diagram is line art. So is a good deal of technical illustration, and so is the sort of logo that has to survive being stamped, embroidered, or cut in vinyl.
The lack of shade is the point, not a failure. Shade is information, and it is also ambiguity. A line says where an edge is and then stops. When the job is to show the edge and nothing else, shade gets in the way. Later, when computers took up the same problem, a vector drawing inherited this economy. Flat pictures and SVG are the machine versions of a decision printmakers had already made.
Illustration
An illustration is a visual representation, a drawing, a painting, a photograph, or some other work, that stresses the subject more than the form. The aim is to elucidate or decorate a story, a poem, or a piece of text such as a newspaper article, traditionally by giving a visual account of something the words have already named. The editorial cartoon, also called a political cartoon, is an illustration that carries a political or social message. It is still an illustration. The message does not put it in a different class of object.
Illustrations turn up in more jobs than people expect:
- giving a face to a character in a story
- showing several examples of a thing described in a textbook
- setting out the steps in a technical manual so the order is visible
- carrying a tone the prose only hints at
- tying a brand to an idea of making, of a particular person, of a way of working
- making a reader laugh
The last of those is easy to dismiss and hard to replace. A joke that depends on a picture fails if you only have the caption. Where graphics are put to use follows that thought into advertising and politics. Charts, maps, and photographs take the other fork, where the picture is asked to report rather than to comment.