Series editors' preface - Wood Tools

504 Conservation of Furniture
can be applied to a range of materials, including
decorated surfaces, ivory and paper. Dry
cleaning methods are particularly appropriate
for porous surfaces. For information on
individual products see Sterlini (1995).
Erasers have been used for cleaning of
paper and painted surfaces (Hackney, 1990)
(Figure 11.7). Most erasers are manufactured
from rubber or polyvinyl chloride and some
contain harsh abrasives. Vinyl erasers are less
harsh than rubber but can contain up to 35%
plasticizer. Two effective vinyl erasers are the
Mars-Plastic (Staedtler) and Magic-Rub (Faber-
Castell). These block erasers are soft, white
and can be cut to a clean or angled edge if
desired. Both contain calcium carbonate and a
phthalate plasticizer that will dissolve in polar
solvents such as alcohol, but can be used with
water or a hydrocarbon solvent if desired.
Sterlini (1995) reported minimal visible
residues and changes to wetting properties
when these products were used to clean
paper.
Smoke or chemical sponges, made from
vulcanised rubber and a very small amount of
detergent, have been used for cleaning paper,
textiles and plant fibres and are effective for
large-scale cleaning of fairly flat surfaces. A
gentle rolling action is used to press a piece
of sponge onto the surface being cleaned.
Groomstick is a processed kneadable natural
rubber product that contains titanium dioxide
but is free from moisture, solvents or chemical
additives. It is particularly useful for the
accurate removal of small areas of surface dirt
or for easily damaged surfaces such as water
gilding. A small amount can be wrapped
around the end of a bamboo stick and rolled
very lightly over the surface. Groomstick is
very tacky and should not be used on poorly
adhered surfaces. No visible residues were
found after cleaning paper with Groomstick
but changes to wetting properties occurred
(Sterlini, 1995).
Draft Clean granules are available in two
grades. The standard grade is derived from
vegetable oil fibre (soybean oil) ground into a
powder, to which 5% or less talcum powder
has been added. These contain no rubber but
there is a small amount of sulphur present.
The ‘x’ grade is a pH-neutral rubber material,
free from sulphur. Both are applied by sprinkling
the granules onto the surface and rolling
them over with a brush. The granules spread
out in use and should be brushed gently from
the surface, taking care to remove any stray
granules that may have lodged in crevices.
Traditional artist’s gum, or Art Gum, is a
polyvinyl compound loaded with factice, a
vulcanized vegetable oil product. It has a
tendency to crumble in use but leaves little
visible residue.
The Canadian Conservation Institute (CCI)
examined the Wishab sponge and reported an
unidentified sticky yellow component, and as
a result it is not recommended for conservation
use. Skum-X (Dietzgen), a draughtsman’s
cleaning powder, may leave significant
residues and is also not recommended.
11.3 Solvent cleaning
Solvents are used for many purposes in
conservation, including cleaning and the application
or removal of coatings, consolidants
and adhesives. Making the most of solvents
requires familiarity with basic principles of
molecular bonding and an understanding of
how the structure of solvents affects their
physical and chemical properties. This information
can be applied when choosing solvents
for specific treatments or to solve cleaning
problems. An introduction to the principles of
solvents and solubility can be found in Torraca
(1975). Solvents included in the following
discussion have been included for illustrative
purposes and it should not be assumed that
they are appropriate for use in conservation.
All matter is made up of atoms that may be
combined together in different arrangements
to make molecules. The forces within a
molecule (intramolecular) that hold it together
may be ionic, covalent or metallic and are
known as primary bonding. The forces that
hold molecules to each other (intermolecular)
are known as secondary bonding and may
involve van der Waals forces, polar or hydrogen
bonding. Molecular bonding is explained
by Moncrieff and Weaver (1992). Primary
bonds are usually stronger than secondary
bonds and this is demonstrated by the approximate
ratio of strength of different bond types
e.g. van der Waals forces: hydrogen bonds:
covalent bonds 1:10:100. Solvent cleaning
involves breaking down secondary bonds that