Series editors' preface - Wood Tools

156 Conservation of Furniture
modified seed lac securing varnish were used
to protect the surface decoration. One was
applied in three to four coats over the painted
or metal decoration to prevent tarnish, enhance
colour and provide gloss and the second was
applied in five to six coats over the whole surface.
The japanned papier mâché that was popular
from about 1770–1870 was decorated using
different materials and techniques to those
described above, though the inspiration was
largely the same – the imitation of work from
Japan. Because early japanning lacked both the
strength and density of its Eastern counterpart,
attempts were made to develop an improved
alternative. In 1757 the Society of Arts offered
a premium of £20 to anyone who could produce
a varnish equal to that of the famous
French ‘verrnisseur’ Guillaume Martin and his
brothers. A stronger, more satisfactory English
varnish evolved based on asphaltum, which is
a slow-drying element from the residue of
petroleum or coal tar. It is also known as pitch
and has been used for coatings since prehistoric
times. Tar varnish was made of a mixture
of linseed oil, resin, wax and asphaltum
thinned with turpentine. This mixture had to
be dried artificially, and as a result, its use on
wooden objects was fairly hazardous. It was in
fact originally developed around 1730 at an
iron foundry near Pontypool in Wales for use
on iron plates. The iron plates were found not
to be a good surface for japanning because the
lacquer easily chipped off the metal. However,
on paper mâché the mixture was much more
successful. The papier mâché would not warp
or crack like wood, but could otherwise be
treated in just the same way.
In the blacking shop the articles were treated
as Henry Clay set out in his patent:
... it is first coated with fine lampblack mixed
with tar varnish, then with tar varnish only,
and when dry scraped with a plane, to remove
all the loose fibrous particles from the surface of
the paper, it is then varnished and well rubbed
between each coat of varnish, to make the
surface quite even. When sufficiently varnished
to form a good even surface, it is placed in the
polisher’s hands, to be polished in the black state
previous to painting. The polishing is performed
by rubbing first with pumice stone to take off
the small dust knots in the varnish, and make it
harden better, then the surface is rubbed with
sand made from pumice stone afterwards with
rotten stone , and if a bright surface is required,
it is produced with the hand, and a little finely
powdered rotten stone ...
The ‘blackers’ worked quickly over the surface
of the object with a large round ‘stovers brush’.
Speed was so crucial to the work that they
could not put down their job until they had finished
the process and could pass the article to
the stove. Each coat of varnish had to be stove
dried. In larger firms, the stoves were small
rooms about 10 ft 10 ft 10 ft with large
iron doors, into which the stove enamellers
could push their trucks to stack the shelves.
The earliest ovens were heated by underground
fires which, because they had to be
stoked from the outside, tended to be warmer
near the outer wall where they were easier to
stoke. Many hours of rubbing and varnishing
were necessary to achieve the brilliant, glossy
finish that was the hallmark of all English
papier mâché. This finish is found not only on
the outside, but on the inside and the back of
an article as well.
Japanning became a popular art among the
ladies of the eighteenth century; various magazines
published articles describing the newest
methods. The Ladies Amusement or the whole
art of Japanning Made Easy (see Pillement,
1959), became a standard source book for
those engaged in decorating japanned wares at
an amateur level, much as Stalker and Parkers’
Treatise was in the late seventeenth century.
Walch and Koller (1997) provide analyses of
German baroque and rococo japanning and an
extensive exploration of their science, technology
and conservation.
4.5 Adhesives
Adhesives are substances capable of holding
other, similar or dissimilar, materials together
by their own agency or, as is often the case in
woodworking, by acting in concert with
mechanical methods such as joints. Hence they
must have good adhesion and good cohesion.
Adhesion is the bond formed between the
adhesive and the substrate (the adherend),
whilst cohesion is the internal attraction of the
adhesive to itself. The effectiveness of an adhe-