Series editors' preface - Wood Tools

applying fresh polish before pulling over to
ensure a flat finish.
Once the surface has been levelled and has
hardened off it may be dulled down using fine
pumice or similar abrasive powder. Some
polishers sprinkle a little powder onto the
surface and use a good quality bristle shoe
brush, working along the grain, to dull the
surface. Others recommend placing the pumice
into a flat container, dampening a cotton pad
with linseed oil, and using the pad to pick up
a little powder, which is then worked in even
strokes along the grain (Oughton, 1982). Still
others recommend working over the surface
with fine (0000) wire wool sometimes adding
a little wax paste to lubricate the surface
(Hayward, 1988). It should be noted that
French polishing was popular because it
produced a glossy surface. Dulling the surface
down is not an essential part of the process
and may be inappropriate in some cases.
Glazing
Glazing was used as a cheap alternative to
French polishing and was used to impart finish
with a high shine without an extended
bodying up procedure. It was often used on
carved, pierced or fretted surfaces and could
be used in the corners of polished panels
where it was difficult to create a smooth shiny
surface by french polishing. Glaze was made
by dissolving gum benzoin in methylated
spirits (50/50 v/v). The benzoin was crushed,
placed in a jar with the methylated spirits and
shaken intermittently over a period of a few
days. When the benzoin had dissolved the mix
was strained to remove detritus. Hayward
(1988) recommends diluting the benzoin until
it is similar in colour to champagne. Glaze
could be applied using a polishing rubber
although strokes should not overlap and a
period of about five minutes was needed
between successive coats. Glaze could also be
applied using a brush or dabbed on with a
sponge (Oughton, 1982).
13.8 Craquelure, crazing and
crocodiling
A byproduct of the ageing process of a transparent
coating is a fine network of cracks
known as craquelure. Craquelure may
Conserving transparent coatings on wood 637
contribute to the patina of an aged surface and
enhance the object’s aesthetic or monetary
value. Crazing describes the excessive cracking
of a varnished surface, such that the surface
below appears disfigured or obscured. Landrey
(1984) has described the treatment of a crazed
surface finish with abrasives. Crocodiling
describes excessive shrinkage of a varnish layer
that results in the varnish contracting into small
islands, exposing the surface beneath. This
effect may also be called alligatoring or traction
crackle. Any material that results in a difference
in drying rate between the surface of a varnish
and the body or interior of this layer will
produce some degree of cracking. The more
exaggerated the difference, the more extreme
the result. Thus thick oil or oil–resin varnish
layers that incorporated excess driers are
(a)
(b)
Figure 13.15 Crocodiling
(a) Crocodiling on a decorative component from a bed
tester. The original red japanning was overpainted black
in the nineteenth century. A second red overpaint has
been applied over the crocodiled black layer. Accretions
of dirt accentuated the crocodiled appearance. (b) An
example of severe crocodiling on a road sign