Series editors' preface - Wood Tools

664 Conservation of Furniture
intended to have a matte finish, select a matte
varnish or add a little matting agent to the
sealant.
A thin gold size may be used to seal the
surface. The size is thinned with turpentine and
may be tinted with yellow ochre, applied to the
surface and allowed to dry thoroughly. Two to
three coats may be brushed on evenly, each
allowed to dry and lightly denibbed to seal the
surface. Some gilders simply apply two or three
coats of a thinned yellow oil-based paint to seal
the surface, rubbing each layer down with a
fine abrasive paper (Wetherall, 1992).
Whatever sealant is used, it should be
applied in thin coats to allow it to soak into
the surface and seal it thoroughly. If the sealer
is too thick brush marks may occur, the
coating will sit on the surface and may appear
lumpy, ill-defined or streaky. The porosity of
the surface must be judged on a case by case
basis and the viscosity and number of sealer
coats adjusted accordingly. If gilding onto an
oil-painted surface, for example, no varnish
need be applied as the surface is already
sealed and ready for the oil size. If gilding
directly onto oak, where the open grain is a
feature in the gilding (for example pre-
Raphaelite picture frames), then thin coats of
sealant should be applied so that the grain
does not become clogged, and more than one
application will be necessary as the wood will
soak up the varnish.
14.3.3 Applying the oil size
Tinting the clear size yellow can allow easy
identification of where the size has been laid
and prevent holidays in the size coat. Tinted
size may be made by adding artist’s quality oil
paint to clear size but this will lengthen the
drying time.
Select a time of day to apply the oil size that
will correspond to the drying time of the size.
The longer the drying time the better the lustre
of the gold will be, but also bear in mind that
the longer the size is left the more susceptible
it will be to dust and abrasions. A fairly stiff
short-haired brush is usually used to apply a
thin layer of oil size to the surface. The size
should be applied in a systematic manner from
the bottom to the top of the surface, thinly and
evenly and avoiding brush marks, drips, sags
or runs. An excessively thick layer will cause
the gold laid over it to wrinkle. Size that has
settled or pooled into the depths and hollows
of the support should be removed. Some
gilders work over the surface with a dry brush
to even out the oil size layer.
14.3.4 Applying gold leaf
The gold leaf cannot be applied until the size
has reached an appropriate level of tackiness.
Several factors may affect the drying time of
gold size, including the thickness of the application,
temperature of the room, viscosity of
the size, airflow over the surface and the
addition of drying or colouring agents. There
are several ways of checking the tack of the
size. The traditional method was to touch the
surface with the hairs on the back of the
fingers – when they were just barely dragged
by the size the surface was deemed ready for
gilding. A second method involves running the
little finger over an unobtrusive part of the
surface – if the surface ‘squeaks’ it is ready.
Either of these methods may be used to assess
whether the surface is touch dry and ready for
gilding. If the gold is laid onto size that is too
tacky or soft, the lustre of the finished work
will be impaired and the gilded surface will
remain vulnerable to scratches and fingerprints
for many days or even weeks. If the tack time
has been missed and the oil size is too dry
for the gold to adhere, then the size must
either be wiped off with white spirit and new
size applied, or allowed to dry thoroughly and
a second layer applied. The varnish coat used
to seal the surface may also have to be
removed and replaced if it has been disturbed
by the solvent.
As with water gilding, loose gold leaf is
applied from the cushion using the knife to
cut the gold and the tip to transport the leaf
from the cushion to the oil-sized surface
(Figure 14.18). The leaf should be laid quickly
and in the same order that the size was
applied, from the bottom towards the top, to
avoid loose, falling leaf adhering to the tacky
work below. Once the gold has been applied
to an entire piece or area, dab the loose leaves
down with a large, soft round brush such as
a large squirrel gilding mop (Figure 14.19).
This mop should only be used for this purpose
and not for water gilding. This will adhere the
loose leaves and fragments of gold into all the