Series editors' preface - Wood Tools

728 Conservation of Furniture
Aqueous cleaning will remove water-soluble
soils and often improve flexibility. It may raise
post-treatment pH because acidic degradation
materials have been removed. Cleaning bath
additives can enhance control of pH during
washing and the removal of dirt. Weak and
fragile textiles may require support during
cleaning to minimize further damage and fibre
loss. Disadvantages of aqueous cleaning
include the possible presence of dyes that are
fugitive or pH-sensitive, and water-soluble finishes.
There is a danger that aqueous cleaning
will cause distortion (e.g. tent stitched canvas)
or result in the shrinkage of cellulosic materials
in the filling or its covers as they are wetted.
Differential drying may cause ring staining
(e.g. crewel work). Textiles that are not sufficiently
robust to be restretched to their original
dimensions should not be aqueously cleaned.
Solvent cleaning will remove oily or greasy
soiling. Systems that include some detergentbound
water, known as charged systems, may
remove some water-based soils as well. Whilst
small quantities of solvents may be used within
a fume hood, large quantities require the use
of a closed system, though the mechanical
action of some large systems may prevent their
use for conservation treatments. Solvent cleaning
has a tendency to over-dry the textile and
humidification may be needed afterwards. As a
general rule, commercial dry cleaning should
be avoided.
Supports
It may be necessary to introduce a supporting
element in cases where the original upholstery
or any of its elements is no longer strong
enough to support its own weight, or where
webbing is being damaged by tension or pressure
from springs. A support may consist of a
solid element introduced to support the structure
from underneath secured with clips,
hooks, tacks or staples (Figure 16.5a,b).
Weakened textiles or cane may be supported
with patches or fully lined with a textile so that
they are stable enough to support their own
weight and reapplication to the unit under the
required tension.
Compression springs incorporated into an
upholstery structure are compressed and tied
down into position with twine. When the twine
degrades, the compression is released and the
springs can burst through the top or bottom of
the upholstery. In such cases individual springs
may be recompressed using three lengths of
wire, secured at equally spaced points around
the circumference of the spring and around the
upper and lower section of the spring.
Supporting or lining materials need to be
both flexible and strong enough not to be
readily deformed by movement in objects. The
materials used often compromise between
these requirements. Factors that guide the
choice of supporting materials include:
• The support material should not contribute
to the further degradation of an object by
chemical or physical means – for example,
it should not give off acidic vapours or
have markedly different responses to environmental
conditions than the material to be
supported
• The support material should be of appropriate
colour, thickness, lustre, ease of
application, availability and cost
• Textiles should be finish-free or have a finish
that is easily removed and should be
easily dyed, if required, using simple methods
and equipment
• The movement and strength of the support
or lining should be compatible with that of
the object, i.e. strong enough to function well
but not so strong that it might cut through or
damage an aged textile – compatibility
remains an important issue during ageing
• The material should have long-term stability
and good ageing properties
• Additions to the object should be able to be
isolated or easily detected on examination
so as not to devalue the item for analysis as
a historical document
• Choice of a support fabric is important as a
fabric that is too thick or heavy may cause
bulkiness, spoil the line of the furniture or
the frame, or prevent a detachable unit, for
example a slip seat, from fitting back into
the main frame
• Hygroscopic properties are a consideration
in choosing a support fabric. Moisture may
be wicked away from the original materials
by the support fabric so that the support fabric
acts as an environmental buffer.
Conversely, moisture absorption may add
weight to the support fabric. Moisture may
also be attracted from the atmosphere by the
support fabric, transferring it to the object.