Series editors' preface - Wood Tools

54 Conservation of Furniture
flame figure of certain softwoods, for example
Douglas fir, when flat sawn or rotary peeled.
The distribution of wood parenchyma in broad
conspicuous bands may, in hardwoods, also
give rise to flame figure known as watered silk.
A similar figure may also be produced in timbers
with alternating layers of different colours,
such as the striped ebonies. The prominence
and decorative effect of figure depend not only
on correct conversion of the timber but also on
the natural lustre of the wood, which is the
ability of the cells to reflect light. Also important,
though not necessarily related to lustre, is
the ability of the wood to take a good polish.
Colour
The colour of a timber, which is important
from a practical point of view, because it may
enhance or detract from the decorative value of
timber, is caused largely by infiltrates in the
cell wall. These may be affected by light, air,
or heat causing the colour of the timber to
change over a period of time. They may also
interact with other materials, as for instance
when oak reacts with iron a marked colour
change may be induced. The infiltrates and cell
contents of some timbers may, during planing,
sawing, sanding and so forth, cause irritation of
mucous membranes or dermatitis which may in
some cases be severe. Mansonia, makore and
teak are particular examples of timbers that
may elicit a more severe adverse reaction. In
other cases a distinctive odour or taste may
render a timber particularly suitable or particularly
unsuitable for a given application.
Taxonomy – the classification of plants
To delve further into the anatomical nature of
wood, generalities must now give way to
specifics, and individual types and species
must be considered at the cellular level.
Taxonomy, the science of classifying living
things, provides a logical approach to studying
the cellular nature of wood, because, as
expected, closely related trees will have similar
wood tissue. It follows that wood identification
is based on the systematic knowledge and
recognition of cell structure.
The plant kingdom is classified into divisions
(phyla), subdivisions (classes), orders, families,
genera and species (Figure 2.3). It is customary
to refer to a tree, or its wood, by its species
name. In the system of scientific nomenclature,
a species is designated by a binomial term consisting
of its genus (generic name) followed by
the species (specific name). The complete scientific
name also includes an abbreviation of
the name of the botanist who first discovered
and classified the plant, although this is frequently
omitted in general texts. For example,
the scientific name for European ash is
Fraxinus excelsior L. The L in this case is an
abbreviation for Linnaeus. Scientific names in
Latin are uniformly accepted in the scientific
world. A species within a genus may be
referred to in general terms by the roman
abbreviation sp. (plural spp.). Each wood of
course has one or more common names in the
local language, and this can lead to confusion
through inconsistency. Use of scientific names
is therefore advantageous, and reference to
authoritative checklists for both scientific and
common names is recommended. The scientific
and common names of woods found in
furniture are given by British Standards
Institution (1974) and Little (1980).
The woods of most temperate zone trees can
be identified to the genus, but among many
genera the individual species cannot be distinguished
on the basis of wood tissue alone. In
such cases the wood is designated by the
genus name followed by the abbreviation sp.
For example, Picea sp. would indicate a
species of spruce.
Within the plant kingdom, timber producing
trees are found in the division Spermatophytes,
the seed plants. Within this division are two
classes, the Gymnosperms and Angiosperms.
Trees belonging to the Gymnosperms (principally
in the order Coniferales) are called softwoods.
In the Angiosperms, a subclass known
as ‘dicots’ (dicotyledonous plants) includes
hardwoods.
Within the Angiosperms, a second subclass,
the monocotyledons or ‘monocots’, includes
such woody plants as palms, rattan and bamboo.
Materials of these plant groups are not
generally thought of under the term timber
and are not included in this discussion.
However, they are used extensively in some
parts of the world, and those that are commonly
encountered in furniture are discussed
in Chapter 3.