224 PAINTING MATERIALS
coarser in texture but is otherwise similar. It is a tough, close-grained hard-wood.
The heart-wood is light brown and the sap-wood is nearly white. The wood is
ring-porous and annual rings are very distinct. In tangential section the rings
produce marked elliptical or parabolic figures. The rays are fine and not conspicu-
ous. The so-called ' mountain ash' (Pyrus) belongs to an entirely different
family. Ash has not been extensively used as a support for paintings (see also
Wood).
Beech (Fagus). The beech usually found in panel paintings of the West is
Fagus sylvatica,) one of the common forest trees of temperate Europe. Fagus
americana is very like it. The wood is not remarkable for either strength or dura-
bility but has been much used in mill-work and turnery. It is heavy and fairly
straight-grained, and is diffuse-porous though the pores are small. Annual rings
are not distinct. The color, particularly that of the heart-wood, is reddish to
reddish brown. On quarter-sawed surfaces the rays are conspicuous as dark
flakes from one sixteenth to one eighth inch in height. Only a few paintings of the
German school are reported to be on beech.
Birch (Befula). This genus of tree is widely distributed over the northern
hemisphere. The white birch (5. alba) is the species most commonly used in
Europe. (It is not to be confused with the paper birch [£. Papyracea] of North
America.) The yellow birch (5. lutea) and the sweet birch (£. lento) are the
species most valued for timber in America. Birch is moderately strong and does
not warp badly. Heart-wood is reddish brown in color. The texture is close and
compact; the pores are diffuse and very small and for this reason the annual
rings are not conspicuous. The rays appear on quarter-sawed surfaces as very
small, Teddish brown flakes. Birch is often stained to imitate mahogany. It has
been little used in panel painting (see also Wood).
Brass, as the term is now used, is an alloy of copper and zinc. The proportion
of the two metals may vary within fairly wide limits, but ordinary brass is about
2 parts copper and I part zinc. In its older use, the term was applied to the alloys
of copper and tin, now known as bronze. The brass spoken of in the Bible was
probably bronze and so, also, was much of the brass of later times until the
distinction between zinc and tin became clearly recognized. Copper-zinc alloys
were known in Roman times. They were manufactured in England in the XVI
century. Although it is probable that brass was used as a support for painting,
along with other metals (see also Metals and, particularly, Copper), no available
evidence for such use appears.
Canvas is, literally, a coarse cloth made from cotton, hemp or flax. This
definition serves well enough to describe the traditional fabric used as a paint
support in Europe (see also Fabrics), though hemp fibre is rarely found in such
objects. The word c canvas * has now a number of meanings. It may be used for
artists' canvas or for a picture painted on canvas.
Cedar (Cedrus). Under the name * cedar * is included a number of woods from
different genera, some of which are not conifers, and the name has been applied