Series editors' preface - Wood Tools

480 Conservation of Furniture
applied to the substrate and allowed to gel
before the design element is applied, using hot
blocks and cramps to secure it. Adhesive
residue from the pressure-sensitive tape may
be removed with white spirit.
The use of an isolating layer, cauls or cramps
and softening blocks is essential when laying
the replacement on to the original surface.
Transparent Perspex/Plexiglass blocks will
allow sight of the work should any adjustments
be needed. A Melinex/Mylar isolating layer
may result in a slightly longer curing time than
if paper and wooden cauls are used. Once the
glue has dried, the isolating layer and any
excess glue are removed before the replacement
is levelled and finished as necessary. The
process of levelling the repair should never
result in the removal of finish or material from
the original surface next to the repair. Tools for
levelling repairs are discussed in section
10.1.11 above.
10.4.6 Lifting original veneer
It may occasionally be necessary to lift an area
of original veneer. One of the most common
faults that causes such interventive treatment is
shrinkage of the substrate (see Figure 10.14).
It must be stressed that there is no long-term
benefit, and a very real risk of causing further
damage, if such treatment is undertaken without
addressing the environmental conditions
that caused the damage in the first place.
A traditional method of lifting marquetry or
boulle involves removing the veneer piece by
piece using a warm iron, sometimes in combination
with a damp rag. A palette knife or
other thin flat metal tool may be used to slide
between substrate and veneer to help separate
them. This requires patience because if an
attempt is made to lift the veneer before the
glue has sufficiently softened the veneer may
split or break. Oyster veneers, composed
entirely of end-grain, are particularly fragile.
The surface finish is often irreparably damaged
and in some cases varnish was removed to
speed the process of veneer removal. A localized
heat source, such as a heated spatula, may
be useful for small areas. Once the veneer has
been lifted the old glue is removed whilst still
soft to prevent distortion and buckling of the
veneer as it dries out. Lifted veneer is stored
between flat weighted boards, with complex
design elements taped together if necessary,
until needed for relaying. Plastic sheets encourage
mould growth if the veneer remains damp
for too long. If the veneer has been allowed to
dry out and has buckled it may be necessary
to spray it lightly with water, place it between
two boards, gradually increasing the weight
and respraying as necessary. Some restorers
have resorted to complete removal of the
substrate, planing or chiselling it from the back
until the undersurface of the veneer was
reached, before relaying the veneer onto a new
substrate (see, for example, Hawkins, 1986).
Two methods that allow the removal of a
marquetry or boulle surface in one piece are
described by Ramond (1989) and Edwards
(1997). The first, called the ‘damp method’, is
particularly suited to boulle. It has also been
used for marquetry, although the extended
exposure to moisture may cause disruption of
the design due to the expansion of individual
elements. A wet cloth is applied to the surface,
covered with plastic and left for about twelve
hours, softening the adhesive and turtleshell
elements, and beginning the process of separating
the decorative surface from the substrate.
The surface is then faced with Japanese paper
and Paraloid B72, which holds the surface
together whilst spatulas and alcohol are used to
release areas that are still adhered to the
substrate. Old glue is removed from both the
underside of the boullework and the substrate.
Kraft paper is stretched in the manner used to
prepare paper for water colour painting. The
paper is evenly wetted and taped to a rigid
support board. It stretches as it dries and this
prevents distortion during the next stage, when
the underside of the boulle is glued to the
paper. Boulle, paper and board are then placed
in a press. When the boulle is flat and dry, the
Japanese paper and Paraloid B72 are removed
using an aromatic hydrocarbon solvent, allowing
access to the boulle for replacement of
losses. The boulle is removed from the rigid
support board and then the upper face glued to
paper as described above. Paper and glue are
removed from the underside, minimizing as far
as possible the length of exposure to water.
The boulle may then be relaid onto a repaired
substrate, glue and paper removed and the
surface refinished as required.
The ‘dry method’ requires the removal of
surface finish as the first step. Thin gauze or a