Pete Dandridge, the conservator for the Met's medieval ivory chess pieces, was also responsible for checking the condition of the Lewis Chessmen when they arrived in New York. We asked him to tell us more about the technique of carving walrus ivory in the Middle Ages.
All works of art strive to alter the perception of the viewer. The most successful meld a unique artistic vision with a thorough understanding of materials and a command of techniques. To discern how artists do what they do so well, conservators draw on a range of resources—including contemporary records of artistic practices, archaeological evidence, previous research, direct observation, and visual and material analyses.
The Lewis chessmen and the medieval chess pieces in the Metropolitan's collection provide an appealing group for such a study, as they were created from similar raw materials with a set of prescribed tools, to serve a common function. Dated to the twelfth century, the Lewis pieces are the earliest Western examples in the exhibition, and their large number (nearly eighty pieces) provides a baseline for the examination of the early medieval carver's approach to the subtractive process of sculpture. Supporting material from the Museum's collection extends the geographic range and chronologic span of the group, allowing us to evaluate whether stylistic changes were just that or whether they were accompanied by or spurred on by technical advances.
The Western chess pieces in the exhibition are carved from ivory derived from the tusks of walrus, and African elephants, or the teeth of sperm whales. All ivory is comprised of four main components—enamel, cementum, dentine, and pulp—with varying proportions of organic and inorganic compounds in each. (For more on ivory, see the earlier post "The Walrus and Its Tusks," by Ross D. E. MacPhee.) Of these four, dentine is the component used for carving—its very fine, dense texture provides an ideal medium for predictable, consistent carving. In pieces like the Lewis chessmen, the ivory's weightiness (or high-specific gravity) was perfectly wed to objects with a low center of gravity. The pieces feel good in the hand and sit solidly when placed on the board.
When first carved, ivory has a translucent white color that becomes more opaque over time. As it absorbs oils from human hands, the surface can acquire a pearly quality. In the case of the Lewis pieces, the variably wet conditions to which the ivory was subjected during burial caused its soluble components to be leached out selectively, and mineral salts like iron to be absorbed, irregularly tinting the surfaces.
While walrus and elephant tusks share a similar slightly curved and tapering shape, elephant tusks are much larger and circular in cross section, while walrus tusks are elliptical.
In addition, while elephant ivory is uniform, walrus ivory has a substantial proportion of secondary dentine, as demonstrated in the cross sections shown above. The secondary dentine is coarser and more variable in texture and color, making it more susceptible to fracture during carving. For this reason, medieval artists working with walrus ivory generally chose to focus their work within the primary dentine. An example can be found in The Cloisters' Cross, on which nearly the entire sculptural program is carved from primary dentine, and secondary dentine serves as structural support:
Compare this with the following image of the crucified Jesus, in which the artist used the textural and visual disparity of primary and secondary dentine to create emotional effect. Jesus's face and loincloth are carved in the smooth, primary dentine, while his chest is carved to expose the cracked secondary dentine, evoking the skin's deathly pallor:
The carver of an ivory chess set would have assessed the valuable raw material carefully before setting to work, especially in light of the various forms and sizes of the chessmen to be realized from the arc of the tusk. The most imposing piece, the King, might have been placed first, to allow for its breadth and height, and to provide enough primary dentine for the modeling of his face:
The breadth of the Knights' horses required the largest dimensions of the tusk from around the pulp cavity:
The entire tusk would have been cut into cross sections as needed to accommodate the various sizes of the chess pieces. While we can see that the artist who carved the Lewis pieces made efforts to utilize primary dentine for significant features, secondary dentine sometimes bisects the face of a King or Bishop. I imagine that at least a few artistic decisions were dictated by the material at hand—whether a Bishop stands or sits might have more to do with available primary dentine than with a predetermined iconographic program.
We have no direct archaeological evidence from the medieval period of ivory working and its associated tools; however, excavated pieces such as the Viking-era tool chest found at Mästermyr in Gotland contained a nearly complete set of woodworkers' tools, including saws, files and rasps, chisels, and auger bits (see images) that, if reduced in scale, would be representative of the tools available to an ivory carver. The techniques and implements employed in medieval carving appear to belong to an abiding tradition of working bone, ivory, and antler, a method further perpetuated by Inuit carvers of the early twentieth century.
A Benedictine monk known as Theophilus, who lived about the time the Lewis chessmen were carved, was the author of the only known treatise from that era about the carving and shaping of ivory plaques and ornaments. In Chapter 93 of On divers arts, he describes applying a chalk ground onto prepared plaques, marking out the design first in lead, confirming it with a scribe or awl, and, finally, carving. In the next chapter, he introduces a lathe (identical to one illustrated in the thirteenth-century Book of Games; see image) to shape decorative finials and knobs that would have resembled the simple geometric forms of many chess pieces. In the illustration, the artist pictured on the left is using a set of gouges and chisels similar to those found at Mästermyr to create a chess board, while his colleague shapes a chess piece on a bow-driven lathe with the cutting tool held in his left hand and with additional pressure applied by his left foot. A shelf above the turner exhibits both carved and lathe-turned pieces.
These referents are helpful when we turn to the objects themselves to examine and interpret their tooled surfaces, which I will discuss in my next post.