Series editors' preface - Wood Tools

142 Conservation of Furniture
ageing properties and overall stability are all
important. The following description includes
the terminology used for different parts of decorative
structures, some examples of the preparations
used and an explanations of the layer
structure of some common types of surface
decoration. For definitions of a wide range of
materials used in coatings see Massey (1967).
4.4.1 Supports
The support is the structural foundation, backing
or carrier for the ground. Supports of decorative
finishes on furniture are mostly wood
but can be leather, metal, glass, stone, ceramics,
papier mâché, or other materials. Supports
may be flexible or rigid and may be more or
less dimensionally stable under the influence
of humidity and temperature. The stability of
the support is of fundamental importance to
the continued survival of the decoration placed
on it.
Stoppings
Stoppings are used to repair small defects in
presentation surfaces of (wooden) supports of
furniture after manufacture, before further finishing.
Historically, stoppings were based on
oil and whiting, wood dust and glue, resin,
wax or a combination of these. A representative
stopping recipe for ‘beaumontage’ for traditional
cabinet work included equal parts of
beeswax and crushed rosin, a few flakes of
shellac and dry pigments heated until the mixture
had melted together and was used hot
(Hayward, 1974). Commercially available shellac
and ‘lacquer’ sticks are available for this
purpose which are melted and dripped into the
hole. Various types of plastic wood, supplied
in tubes and cans, often contain cellulose and
a quick drying synthetic resin binder. Two part
wood stoppings that set with a catalyst are also
available. Stoppings based on natural resins
may have a tendency to crack and become
brittle. Wax-based stoppings may be too soft
for normal wear and could inhibit the adhesion
of later finish work. Two part stoppings set by
chemical reaction and may therefore be difficult
to remove.
Grain fillers
Grain filler does not form a continuous layer
over the surface and is not technically a
ground. Many different materials have been
used to fill the grain of wood before polishing
or painting, to prevent the finish sinking, to
economize on materials and time, and to prevent
grain showing. The use of brick dust is
referred to by Sheraton in the Cabinet
Dictionary (Sheraton, 1970) as a means of filling
the grain partly with the dust itself and
partly with wood fibres detached from the surface
of the wood. Pumice can be used to the
same end. Other materials include plaster, various
resins and commercial grain fillers. There
are many brands of filler available commercially.
These divide into oil based fillers, composed
of natural or synthetic resin and tung or
linseed oil binders, and those containing a
water-based finish (e.g. acrylic) as a binder. In
either case, the bound solid is normally silica.
An appropriate pigment is normally added to
match the colour of the wood being filled.
4.4.2 Grounds
Grounds are layers or coats applied to the support
to provide a suitable surface on which to
paint or gild. Three important grounds in
European and American painting are oil
grounds, gesso grounds and emulsion grounds,
though there are others (Massey, 1967). The
ground fulfils some important functions. First,
it buffers the surface decoration from the
hygroscopic movements of the support, particularly
important with wood. Secondly, it provides
a smooth surface for painting or gilding
and may itself be decorated with recutting or
punch work. Thirdly, it gives a unified light
colour against which the decoration is reflected
and finally, the elasticity of the ground may
permit burnishing of gold leaf applied to the
surface. Different types of surface decoration
require different grounds and these choices are
determined by the intended use and cost. A
traditional gesso ground, for example, is
required for high quality water gilding, but oil
gilding destined for an exterior location can be
applied on a primer paint.
Gesso grounds
Gesso consists of an adhesive with an inert
filler. Traditionally, animal glue is used as the
adhesive but gesso can be based on casein,
acrylic or other materials. The term gesso originally
referred to a gypsum- (calcium sulphate)