Series editors' preface - Wood Tools

the addition of a separate thixotrope, or, more
commonly in conservation, the surface of bare
wood can be pre-sealed. It may be possible
to manipulate gloss as a surface coating cures
by removing a small amount of the upper
layer of a coating or disturbing the surface
when it has not completely cured by lightly
padding it with a finger to create a textured
surface. Misting on a top layer of resin from
a spray gun may reduce surface gloss, as will
increasing the distance from the object when
spraying on a coating. A combination of these
gloss modification techniques can be used in
to create an appearance consistent with the
age and appearance of the object.
Many historical sources refer to the use of
powdered abrasives to polish or dull a
varnished surface. Powdered abrasives vary in
hardness, size and colour. Harder abrasive
particles will remove more of the surface with
each comparable motion, but particle size will
determine whether the scratches produced will
be visible. Thus aluminium oxide (Mohs
hardness 9) will remove more material than
jeweller’s rouge (iron oxide, Mohs hardness
5.5–6) but if the particle sizes are the same,
the surface appearance will be similar. The
abrasive effect of particles on a surface is
ameliorated by the presence of a lubricant,
such as solvent or a small amount of wax.
Precautions must be taken to avoid inhaling
abrasive powders or abraded dust.
Pumice, rottenstone, tripoli and crocus
powders, precipitated chalk and diatomaceous
earth are traditional abrasive powders (see
Table 10.3). Pumice comes in several grades
but even the finest is often too coarse for
transparent surfaces. Rottenstone has been
used by finishers for centuries as a way to
bring a gloss to a surface (Byington
manuscript, c.1780). Modern materials include
aluminium oxide, which can be purchased
according to particle size, from 0.05 to 5 μm.
Transparent Plexiglass or Perspex may be
used to carry out an empirical evaluation of
the degree of scratching produced by different
materials. Differences may be more easily
visible under UV or raking light than under
diffuse natural light. Matte black paper underneath
the plastic may also be helpful.
It may be difficult to fully remove powdered
abrasive from a surface that has fissures in the
coating though a small amount of pigment or
Conserving transparent coatings on wood 639
dye may be added to make such residues less
obtrusive. This problem is less evident with
abrasive papers since the abrasive is bound to
the backing.
13.10 Distressing
Distressing describes the simulation of wear,
minor damage, stains and accumulated dirt on
a new surface, so that it resembles an aged
surface. Many texts on furniture restoration
describe methods of distressing repairs in
order to simulate age and wear. These can
include beating the new wood with bicycle
chains, rocks, keys, barbed wire etc., though
the effects are often a very poor imitation of
the original. Examples of poor distressing
include simulating wear evenly on all four
arrises of a chair stretcher rather than concentrated
on the upper front edge, or the repetitive
denting of a surface with the same mark
(e.g. a hammer). If distressing is to be undertaken,
an old surface should be examined
carefully and the type of wear or damage a
surface or component would be likely to
receive considered. Sharp or sanded edges to
dents are rarely appropriate. Surface damage
usually occurs long after polishing with the
result that dirt is trapped above the surface
finish, rather than below it.
Age and accumulated grime may be
simulated using a thick solution of Vandyke
stain (see, for example, Bennett, 1990). Inert
powders such as rottenstone or dry earth
pigments may be dusted into recessed areas.
Some earth pigments present a health hazard
(e.g. raw umber) and the supplier’s or
manufacturer’s material safety data sheet
should be consulted (McCann, 1979). A resin
binder, preferably with different solubility
parameters from the surface coating, may be
used to selectively apply particulate material.
The success of a matching a repair often
depends on the finesse of adding and subtracting
from the upper surface until the right
visual qualities are achieved.
Bibliography
Abercauph, C. (1998) Wax as a surface coating, in W.
Samet (compiler), Painting Conservation Catalogue: