Series editors' preface - Wood Tools

752 Conservation of Furniture
more resistant to dissolution than a coating
composed of the same binder. Bronze powder
retouchings, for example, often bound with an
oil–resin mixture, were often applied to both
water and oil gilded surfaces. As the binder
ages and oxidizes it becomes more acidic and
can catalyse the corrosion and discoloration of
the metal flakes in the bronze paint. Metal salts
can form within the film and crosslink it, making
it even more difficult to swell or disperse in
the solvents or solvent blends that might otherwise
be expected to have an effect.
Where the retouch is very resistant it may be
necessary to combine mechanical removal with
the use of an alkali such as ammonium hydroxide,
Vulpex (an alkaline detergent) or a chlorinated
solvent such as dichloromethane. In the
past dimethyl formamide has been a last resort
but the toxicity of this solvent usually precludes
its use. These materials work because
they are strongly alkaline or very polar, but as
such carry the very real danger that they will
damage the original surface where they come
into contact with it. Commercial paint strippers
are often formulated with methanol, methanol
chloride, toluene or dichloromethane, and may
contain water and a surfactant. They are often
effective in removing overpaint but will also
tend to damage underlying original material.
The more aggressive the removal method used,
the more risk of damage to the surrounding
paint. It may be a more ethical decision to
leave the retouch intact rather than risking
damage to the surrounding original decoration.
16.6.5 Consolidation
Paint surfaces that are flaking or friable often
require consolidation before the surface is
cleaned. Flaking, peeling and lifting paint can
be treated by introducing a consolidant under
the paint film to renew the adhesion of the
paint film to the substrate and prevent further
losses. The choice of consolidant is determined
by the condition and sensitivity of the surface.
Although wax has been used as a consolidant
in the past, it is a poor adhesive and limits
future treatment options and is therefore not
recommended as a consolidant for painted surfaces.
Where it has been used as a consolidant
in the past it may be necessary to re-treat using
wax or Beva 371. Common materials used for
the consolidation of paint on wood include
protein based consolidants such as gelatin,
sturgeon glue or isinglass, methyl cellulose,
PVAC, acrylic dispersions and acrylic resins
such as Paraloid B72. The advantages and disadvantages
of common consolidants are discussed
in section 12.2.4.
16.6.6 Reintegration
Samet (1998) has contrasted approaches to the
aesthetic reintegration of paintings and painted
furniture. Infilling and retouching media
should ideally possess different solubility parameters
from the original paint and be separated
from it by a reversible isolating layer. They
should also be undisturbed by the application
of a final coating. Materials and approaches to
infilling and retouching are considered in section
12.3. It is important to consider the sensitivity
of the surface because a fill can act as a
solvent reservoir and swell or damage adjacent
original paint. Infilling of losses to painted surfaces
may utilize a collagen, PVAL, PVAC or
Paraloid adhesive and traditional whiting or
microballoons may be used as a bulking agent.
Aqueous pastes such as collagen or PVALbased
fills are often similar in density to gesso
type grounds and are easy to manipulate,
apply, level and clean up around the fill.
Commercial spackles, which may be based on
an acrylic dispersion, are used by some, but as
with other fills, should be isolated from the
original to ensure future reversibility or
retreatability. A range of commercial vinyl and
acrylic fill materials have been evaluated by
Craft and Solz (1998).
16.6.7 Coatings
Common materials used for the coating of
painted surfaces, their advantages and disadvantages,
and application methods are discussed
in section 12.4. It is essential that the
final surface of the object is appropriate to current
knowledge of its historical appearance.
Coatings that appear to be thick, plastic and/or
excessively glossy may be inappropriate for
painted furniture. Painted furniture that is to be
used or displayed in a domestic context may
require a harder wearing coating than that
needed for a museum context.
The application of varnish can result in
leaching of paint films in a similar manner to