Series editors' preface - Wood Tools

Table 5.2 Relationship between composition and
colour of different metal leaves
Colour/carat % Gold % Copper % Silver
(Au) (Cu) (Ag)
Red 23.5ct 98 2
Medium deep 22.75ct 95 2.5 2.5
Pale yellow 22ct 92 1 7
Yellow 24ct 100
Lemon 18ct 75 25
Green 14.5ct 60 40
White 12ct 50 50
Silver 100
of 20 books. The size of the leaf is usually
85 mm (3 3 ⁄8 in.) square, but may vary between
60 and 110 mm depending on the individual
goldbeater. Thickness varies between 0.36 and
0.8 μm. One troy ounce (31.1 g) of gold will
produce about 80 standard books of gold leaf,
that is 2000 3 3 ⁄8 in. square leaves.
The thinnest gold was produced at the end
of the nineteenth century and beginning of the
twentieth. At this time, workshops were
numerous and prosperous, allowing more
specialization of tasks. This increased the skill
of the beaters so that they could produce very
thin leaves. There was a correspondingly high
level of skill in gilders, who perfected the art
of handling such fine leaves. Transfer or
patent leaf is similar to loose leaf but is lightly
adhered to non-rouged tissue by pressure or
wax. Leaves of gold cold-welded together are
sold in rolls, in widths from 3 mm to 135 mm
and up to 21 m in length, for use in bookbinding
and architectural gilding.
‘Regular’ gold is a colloquial term for the
gold beater’s ‘own brand’ and will vary
between establishments in colour, carat and
thickness. Double-weight gold is a thicker leaf
of 22 carat or more used for exterior gilding
and for areas of high burnish. Though called
double-weight, the leaf in fact contains no
more than 10–15% more metal than standard
leaf. Again, the leaf varies according to the
beater, for instance one goldbeater’s regular
gold maybe just as thick as another’s double
weight. A high carat gold is recommended for
exterior use to reduce tarnishing.
Shell and powdered gold
Shell gold and powdered gold are made from
either gold leaf or the skewings thereof. Shell
Other materials and structures 211
gold is powdered gold mixed with gum arabic
and water. This paste was traditionally allowed
to dry naturally in mussel shells (the source of
its name), which acted as both a container and
a palette. It is now sold as small blocks
(0.33 g) on white plastic palettes. It dries to a
dull lustre and has a slight tendency to look
like bronze powder. Its advantage, however,
is that it does not tarnish and it can be lightly
burnished. Powdered gold is pure gold with
no binder. It adheres either by the gilder
breathing onto the area to be gilded, or by
application onto a wetted surface. Its advantages
over shell gold are that it is much
brighter and can be more highly burnished. It
is bought in 1 and 2 g packages in a limited
range of colours, but other colours can be
made by the gilder.
Finishes and coatings on metals
Ferrous metal objects could be left with the
lustrous black fire scale formed by oxidation
in the forge, adhering to the surface. As such
they were the work of the blacksmith. They
could also be ground, filed, and polished to a
high shine by the whitesmith.
Coatings of tin have always been popular
on iron and copper alloy objects and could be
achieved by hot-dipping or by rubbing the
molten tin onto a clean, hot and fluxed metal
surface. Thin tinned-iron sheet was made in
large quantities in the area of south Wales
from the early eighteenth century. Tinned-iron
sheet (tin plate), often commonly called
simply tin, was used to make pierced screens
for food storage furniture. Tin-plate tends to
rust through in spots, so a coating of zinc
(galvanizing) was commercially used on iron
after about 1838. A zinc coating will continue
to protect the iron from corrosion as long as
any metallic zinc remains, unlike tin which
will actually accelerate corrosion of the iron
once it has been exposed.
Electroplating of one metal onto another by
use of a direct current became common after
1840 although electrochemical plating using
metallic salts can be dated from at least a
thousand years earlier. Nickel plate on both
iron and copper alloys has been popular for
decorative hardware since the late nineteenth
century.
Before the invention of electroplating,
gilding on metals was most commonly