An Investigation Toward the Identification of Traditional Drawing Inks

Bistre, carbon, sepia and iron gall inks are all present in old master drawings. The manufacture and characteristics of these inks are discussed and visual clues which aid in the identification of the media are reviewed. Drawing inks of known composition were analyzed with x-ray fluorescence spectroscopy and Fouriertransform infrared spectrometry. Case studies of examinations of ink drawings are presented to illustrate how these methods can be used together to identify inks of unknown composition. INTRODUCTION The identifying term "brown ink" is commonly used in the cataloging of master drawings. This broad descriptive term does little to indicate the richness or variety of tones of the inks which fall within this category. The goal of this study was to build on~xisting strategies for the identification of traditional drawing inks with the use of non-sampling analytical methods. This investigative project originated during an advanced internship at the Fogg Art Museum's Center for CoQ.servation and has continued during my current Mellon Fellowship at the Art Institute of Chicago. Traditional brown inks have differences in tonal range and handling qualities which artists have used with effect. This is most notable when inks of different composition are used in combination on a single drawing. A popular working mode is the application of a thin ink wash to establish composition, followed by darker lines, applied to define elements within the drawing. Ink drawings which have been re-worked with a secondary ink invite technical investigation. The determination of whether the drawings were altered by the original artist, or later by a second hand, should be made cautiously and collaboratively with art historians. Regardless of the reason for the presence of more than a single ink on a drawing sheet, the occurrence is sufficient reason to question differences in ink types and regard variances in their aging qualities. If an ink which fades on exposure to light appears next to an inert pigment, the comparative aging will unquestionably alter a viewer's perc~ption of the artist's intent. 9 COMPOSITION, WORKING PROPERTIES AND CHARACTERISTICS Inks can be either dyes or liquid suspensions of fine pigments; they are delivered to paper evenly by pen, or built up in washes by brush. The distinction between ink and watercolor can be somewhat tenuous and the drawing media are defined more clearly by historic characterization than by use or material composition. The general types of brown ink addressed by this study are bistre, sepia and iron gall. The goal was to differentiate between these general ink categories while being mindful of the untold variations within each type. The foundation of a technical study of artist's materials is an understanding of the manufacture and the working properties of the materials in question. Throughout this study, consideration was made of other inks of historic use. Before contemplating the brown inks, it is worthwhile to reflect on the black ink which is so often found in their company. CARBON INK Carbon ink is an aqueous suspension of flame carbon, or lampblack, obtained from soot. The pigment was ground with a binder, such as glue, gum or shellac to facilitate the storage of the ink in the form of a cake or powder. When manufactured in an artist's studio, the source of the pigment was commonly the soot which was collected from a dish held over the flame of a candle. Cennini (1960) also refers to the use of soot obtained from the burning of almond shells and peach stones. The greasier the soot component, the less binder is necessary for its manufacture. The ink has bluish undertones and indigo was sometimes added to make the washes appear more grey (Constable 1954). This ink is remarkably stable due to the inert nature of carbon. References exist to the use of carbon ink in China as early as 2500 B.C. BISTRE Bistre, also known as brown lamp black or soot brown, is made from tarry soot collected from a wood chimney. Soot from the burning of beechwood was most popular for this use. It was dissolved in hot water and cold filtered. Cooling the mixture prior to filtering allowed the sedimentation of soot in the container, avoiding the expansion of the filtering paper's fibers, which would allow more particles to pass through, resulting in a less complete separation of the mixture