Although all dyestuffs of low viscosity lend themselves to pen drawing, the various inks are most often employed. The manufacture of gallnut ink had been known from the medieval scriptoria (copying rooms set apart for scribes in monasteries). An extract of gallnuts mixed with iron vitriol and thickened with gum-arabic solution produces a writing fluid that comes from the pen black, with a strong hint of purple violet, and dries almost black. In the course of time it turns a darkish brown, so that the writing fluid in old manuscripts and drawings cannot always be identified by the colour alone. In contrast to other brown writing fluids, the more strongly coloured parts of gallnut ink remain markedly darker; and because inks of especially great vitriol content decompose the paper, the drawing, particularly in its more coloured portions, tends to shine through on the reverse side of the sheet. Only industrially produced chemical inks possess the necessary ion balance to forestall this undesirable effect.
Another ink, one that seems to have found no favour as a writing fluid but has nonetheless had a certain popularity in drawing, is bistre, an easily dissolved, light-to-dark-brown transparent pigment obtained from the soot of the lampblack that coats wood-burning chimneys. Its shade depends both on the concentration and on the kind of wood from which it is derived, hardwoods (especially oaks) producing a darker shade than conifers, such as pine. During the pictorially oriented Baroque period, in the 17th and early 18th centuries, the warm tone that can be thinned at will made bistre a popular medium with which to supplement the planes of a pen drawing.
Also derived from a carbon base is India ink, made from the soot of exceptionally hard woods, such as olive or grape vines, or from the fatty lampblack of the oil flame, with gum-arabic mixed in as a binding agent. This deep-black, thick fluid preserves its dark tone for a long time and can be thinned with water until it becomes a light gray. Pressed into sticks or bars, it was sold under the name of Chinese ink or India ink. This writing fluid, known already in Egypt and used to this day in China and India, has been manufactured in Europe since the 15th century. Favoured in particular by German and Dutch draftsmen because of its strong colour, it lent itself above all to drawing on tinted paper. Since the 19th century, India ink has been the most popular drawing ink for pen drawings, replacing all other dyestuffs in technical sketches. Only very recently have writing inks gained some significance in art drawing—in connection with the practical fountain pen.
For a relatively short time, a dyestuff of animal origin, sepia, obtained from the pigment of the cuttlefish, was used for drawing. Known since Roman times, it did not come into general use until the 18th century. Compared to yellowish bistre, it has a cooler and darker tone, and is brown with a trace of violet. Until the 18th century, it was employed by such amateur painters as the poet Goethe because of its effectiveness in depth; as a primary pigment, however, it has been completely replaced by industrially manufactured watercolours.
Other dyestuffs are of only minor importance compared with these inks, which are primarily used for pen drawings. Minium (red lead) was used in the medieval scriptoria for the decoration of initial letters and also in illustrated pen drawings. Chinese white is easier to apply with a pointed brush because of its thickness; other pigments, among them indigo and green copper sulfate, are rarely found in drawings. For them, too, the brush is a better tool than the pen. The systematically produced watercolours of various shades are almost wholly restricted to technical drawings. Pen drawings
In combination with written texts, pen drawings are among the oldest artistic documents. Already in classical times, texts were illustrated with firm contours and sparse interior details. During the Middle Ages, marginal drawings and book illustrations were time and again pre-sketched, if not definitively executed, with the pen. In book painting, decidedly delineatory styles developed in which the brush was also employed in the manner of a pen drawing: for example, in the Carolingian school of Reims, which produced the Utrecht Psalter in the 9th century, and also in southern Germany, where a separate illustrative form with line drawings was widespread with the Biblia Pauperum (“Poor People’s Bibles,” biblical picture books used to instruct large numbers of people in the Christian faith). The thin-lined outline sketch is also characteristic of the earliest individual drawings of the late Middle Ages and early Renaissance. Sketches after ancient sculptures or after nature as well as compositions dealing with familiar motifs form the main themes of these drawings. Such sheets were primarily used as models for paintings; gathered in sketchbooks, they were often handed on from one generation to the next. The practical usefulness of these drawings is attested by the supplements added to them by younger artists and by the fact that many metalpoint drawings that had become hard to decipher were redrawn with the pen, as shown by the sketchbooks of the 15th-century Italian artist Antonio Pisanello, now broken up and preserved in several different collections.
In the 16th century, the artistic range of the pen drawing reached an individual articulation that it hardly ever attained again. Every artist was free to exploit with the pen the formal possibilities that corresponded to his talents. Thus Leonardo used a precise stroke for his scientific drawings; Raphael produced relaxed sketches, in which he probed for forms and variations of form; Michelangelo drew with short strokes reminiscent of chisel work; Titian contrasted light and dark by means of hachures laid broadly over the completed figures. Among the Northerners, Dürer mastered all the possibilities of pen drawing, from quick notation to the painstakingly executed autonomous drawing, ranging from a purely graphic and delineatory technique to a spatial and plastic modelling one; it is no wonder that he stimulated so many other artists. The subjective attitude of the later 16th century is often expressed more clearly in Mannerist drawings—characterized by spatial incongruity and excessive elongation of the human figures, which are as revelatory of the artist’s personality as handwriting—than it is in completed works of painting and sculpture. A special form of exact drawing is found in models for engravings; some of these were directly mounted on the wood block; some anticipate the style of the copperplate engraving in the pen-drawing stage, with waxing and waning lines, delicate stroke layers, and cross-hatching for spatial and plastic effects.
In the 17th century, the pen drawing took second place to combined techniques, especially wash, a sweep or splash of colour, applied with the brush. An open style of drawing that merely hints at contours, along with contrasting thin and powerful strokes, endowed the line itself with expressive qualities. In his numerous drawings, Rembrandt in particular achieved an exceedingly subtle plastic characterization and even light values through the differentiation of stroke layers and the combination of various pens and brushes.
Additional techniques came to the fore in the 18th century, with the pen sketch providing the scaffold for the drawing that was carried out in a pictorial style. Only decorative sketches and practical studies were laid out more often as linear drawings.
The closed, thin-contour drawing regained its importance with Neoclassicism at the end of the 18th century. The Nazarenes (the nickname of the Lucas Brotherhood—later Guild of St. Luke, who lived in monastic style) and Romantics consciously referred to the early Renaissance manner of drawing, modelling with thin lines. With closed contours, carefully set hair-and-shadow strokes, and precise parallel hachures, they attained plastic values by purely graphic means.