Series editors' preface - Wood Tools

Retouching may involve reproducing not just
the colour of the original, but also the translucence
and reflective properties of the surrounding
area, and in some cases, texture. The
retouching materials and techniques discussed
in section 12.3.2 may be useful, with the proviso
that those in a non-polar binding medium
will have the least potentially detrimental effect
on adjacent lacquer. One of the characteristics
of Oriental lacquer that proved so attractive to
Europeans in the past, the translucence of the
surface, is one of the characteristics that can
cause difficulty when retouching. It may be
possible to partially simulate this property with
a gradual transition from pigment-rich to
medium-rich layers. This process will be
assisted if the retouch medium can be abraded
smooth between layers. Some paints mediums,
such as the Intenso range, may be burnished
instead of abraded. This can be helpful
because the retouching is easier to level and
the burnished paint can simulate Oriental lacquer
better than a gloss medium. Webb (1994,
1998, 2000) reported success using dyes and
pigments in an acrylic emulsion. Natural resin
varnishes such as dammar, and the traditional
furniture retouching medium, shellac, can be
used, though they have a tendency to yellow,
and will develop craquelure as they age.
Stabilized hydrogenated hydrocarbon resins,
discussed in the section on synthetic low molecular
weight varnishes (section 12.4.7), may
be a better alternative. They can be applied
and removed without exposing the lacquer to
polar solvents and are more photochemically
stable than their traditional counterparts.
16.8.9 Restoring a degraded matte
surface
In some cases it is possible to remove a thin
upper layer from a degraded and dull lacquer
surface in order to restore a degree of gloss to
the surface. Such treatments are not generally
recommended because they may damage decoration
and are irreversible. In addition, some
subtleties in the original design may be lost
and the restored surface may not accurately
represent the age or history of the object. As
with Western furniture, signs of age may add
to a lacquer object’s financial and historical
value. Some collectors prize dull surfaces as an
indication of age. The decision to restore a
Conserving other materials II 769
matte surface should only be taken in consultation
with an owner or curator. Speculative
restoration should be avoided. Care should be
taken to avoid localized treatment that may
result in a patchy appearance.
Two approaches can be used. In the first, the
surface of the lacquer is rubbed gently with a
soft cotton cloth slightly dampened with water,
until the upper layer of lacquer that has been
dulled by photo-oxidation is removed (see section
16.8.5 on removal of surface dirt and accretions).
The second method makes use of
abrasives. If the surface of the Oriental lacquer
is treated with abrasives, only those that are soft
and have finely divided particles should be
used, in combination with a lubricant such as
white or mineral spirits (see Table 10.3).
Progress should be checked frequently by
clearing the surface of slurry and examining the
effect. Abrasives may be applied on a small pad
made from high quality cotton wool and a soft
cotton cloth. The method illustrated in Figures
13.12 and 13.13 for making a French polishing
rubber can be adapted for this purpose. Swabs
are not recommended because they may cause
excessive localized abrasion. Proprietary abrasive
mixtures should be avoided because the
abrasive particles are often large, excessively
hard and may irreversibly damage lacquer surfaces.
It is important to ensure that all residues
of cleaning materials are removed when the
treatment is complete.
16.8.10 Coatings
The decision whether to apply a coating to a
lacquer object after a conservation treatment
must be taken on a case-by-case basis after
considering conditions of use, display or storage.
Although there may be occasions when
the application of a coating is appropriate, as
a general rule coatings should not be applied
to lacquer unless they meet a specific need and
can be removed in the future without damaging
the original surface. Restoration coatings
are rarely consistent with the original intended
appearance and may be misleading to an inexperienced
viewer.
If a coating is applied, its intended role
should be clear. If a coating is to provide a UV
barrier, for example, it must incorporate a UV
inhibitor as transparent coatings per se do not
prevent the transmission of UV to the substrate.