258 PAINTING MATERIALS
without regard to the composition of the material, but in connection with its
location and purpose. Modern stucco often consists of small stones bound with
Portland cement. Occasionally the term is applied to surfaces prepared from an
inorganic filler and animal glue, in which case it is practically svnonvmous with
the term * gesso ' when that is used in the broadest sense.
Support, a term used to designate the physical structure which holds or carries
the ground or paint film of a painting. Panels, canvases, walls, and any of the
flat expanses on which paintings can be made, fall under this heading.
Sycamore is the name of a wood which is identified with three species of
tree: (i) Ficus sycomorus, a species of fig tree common in Egypt, Syria, and else-
where, was widely used for general purposes in ancient Egypt. Lucas (p. 387)
notes that it was used in the construction of coffins. (2) Acer pseudoplatanus has
no connection with the Ficus sycomorus^ but is a large species of maple common
in England and on the Continent. (3) Platanus occidentalis is the North American
button-wood or plane tree. The name * sycamore * has been applied erroneously
to both of these. In the latter the heart-wood is reddish brown in varying degrees
and is often not clearly defined from the sap-wood, for the pores are diffusely
placed. The wood is heavy, lock-grained, and has a tendency to warp unless
properly seasoned. There is a distinct demarcation between the spring-wood and
the summer-wood although the pores are diffusely placed. The rays are nearly
all broad, dark, and conspicuous and many are more than twice as broad as the
average pore. The sycamore fig was undoubtedly used as a support for painting in
many of the Egyptian mummy portraits from the Fayum district.
Terra-Cotta is a term applied to baked clay products and these may vary
widely in composition. In modern, technical usage * terra-cotta' means those clay
products used for structural, decorative work that can not be formed by ma-
chinery. In sculpture, particularly of the Italian Renaissance, it made a surface
that was usually painted. It seems not to have furnished a support, however, for
independent designs.
Twill, a weave of fabric in which a series of regularly recurrent warp threads
pass in echelon over and under the weft threads, one after another and two or
more at a time, producing diagonal ribs or stepped patterns (figure I, p. 228).
Vellum (see also Parchment), a fine kind of parchment made, according to
some definitions, from calfskin; according to others it is from the skins of new-
born or still-born calves, kids, or lambs. Generally it is applied to any moderately
good skin that is used for writing or painting.
Walnut (Juglans) is a wood derived principally from two species of the genus.
The European walnut (J. regia) ranges from England to the Far East. That im-
ported from the Caucasus (Circassian) has always been the finest in quality. The
heart-wood is fawn-colored and numerous dark brown or black streaks are present;
these streaks determine the figure of the wood. It is heavy and straight-grained.
Although the spring-wood pores are large and clearly visible, it is not a distinctly