Series editors' preface - Wood Tools

684 Conservation of Furniture
handles on carcase furniture. Furniture that
survives with its original hardware intact
usually has increased historical and monetary
value. Metal components replaced during a
conservation treatment should be given a
durable unobtrusive mark, such as stamping or
engraving, to indicate their non-original
nature. Such marking should include dating
where possible (Figure 15.6).
Some small firms offer a casting service and
use an original fitting as a pattern from which
a replacement is cast. Since metals shrink
slightly on cooling, the replacement will be
slightly smaller than the original. In other
cases it may be possible to purchase a replacement
from specialist suppliers but as a general
rule these require some finishing by the
conservator before they are fixed to the object.
This may involve, for example, the addition of
a bevel to the backplate of a drawer handle
or polishing the surface, having first closely
inspected such details on the original fittings.
Electrotypes can be made from existing
elements by electrically depositing metal into
a mould made from an existing element. This
technique produces a metal copy without any
shrinkage, which can be bent, soldered etc.,
and is faithful to the original in all details.
Copper electrotyping is easy and safe in a
small lab setting.
There are a wide variety of colours and
effects that may be used in the patination of
metal replacements. The one proviso in regard
to patination is that conservators should be
wary of conjectural restoration where no original
exists. Conservators are encouraged to
consult specialist texts (Hughes and Rowe,
1982), restoration manuals (Bennett, 1990;
Rodd, 1976) historical treatises (e.g. Smith,
1810; Spons Workshop Receipts, 1873 etc.) and
sources in related disciplines such as engineering
and horological manuals. It should be
borne in mind that chemically patinated metal
may need to be thoroughly rinsed and dried
to remove residues that might otherwise catalyse
corrosion. Toning using dyes and transparent
coatings is also often effective.
In some cases it may be sufficient, if time
allows, to thoroughly clean the surface and
then leave the metal to slowly oxidize.
Proprietary patinating mixtures such as ‘gun
blue’ have been used for arms and armour.
Brass has been toned using a wide variety of
materials including proprietary products such
as the Armatone range, copper nitrate and
spirit stains in shellac. A simple method of
removing the high shine from new brass is to
simmer the part in deionized water. The oxidation
layer thus formed will be even and stable.
In some cases replacements may be cast
using the materials described in section 10.5.
Polyester resin or epoxy resin may be
coloured using metal powders. The metallic
effect is particularly convincing if these are
dusted into a rubber mould prior to pouring
the resin. In addition to these materials, it may
be possible to cast a replacement using low
melt (‘white’) metals such as tin/lead alloys or
pewter.
Epoxies and polyesters are often chosen for
filling large losses in metal objects. They may
be cast separately and adhered into place, or
cast in place using techniques borrowed from
glass conservation. Epoxies should be isolated
from direct contact with the metal (see section
15.3.5). Glass fibre cloth or randomly oriented
glass fibre ‘mat’ may be used to reinforce fills,
or used to support fills as they are modelled in
place. Epoxies bulked with microballoons are
very useful because the density and weight may
be more sympathetic to damaged, corroded and
weak metal, and they are more easily carved,
filed and manipulated after curing. Denser
epoxy putties such as Pliacre (grey) and
Milliput (white) may be useful in some
instances, and can be made less dense by the
addition of microballoons by the conservator.
15.3.7 Application of coatings after
conservation
There has been some debate in the field of
metal conservation about the appropriateness
of lacquering. Some metals or types of object
have traditionally been lacquered whilst others
were not. Some metals surfaces are not
suitable for coating, e.g. blued steel and other
patinated finishes. Consideration should also
be given to ease of future removal.
Small amounts of water, ions, pollution and
oxygen that penetrate a coating applied to
metal may cause corrosion to occur at a
similar rate to bare metal. The protection
offered by a coating is dependent on several
factors, including physical and chemical
properties and resistance to the permeation of