Series editors' preface - Wood Tools

274 Conservation of Furniture
previously. Conservation treatments are expensive,
involve further risk to the object and do
not replace lost information. Direct contact
with an object can result in transfer of material
between the handler and the object.
Corrosion or other chemical reaction of the
object may be caused or made worse by
contact with moisture, salts, acids and dirt
present on skin. Vulnerable surfaces include
gilding, lacquer, metalwork and ‘sick’ glass.
Staining and marking of objects containing
materials such as paper, card and unglazed
ceramics may be caused by skin contact.
Contact with jewellery or other hard metal
items worn by the handler may snag or
damage delicate surfaces. Contact with soiled
material present on the surface of an object,
for example fumigant or pesticide residues or
toxic pigments, may be hazardous to people.
Clothing
It is advisable to wear clothing that allows free
movement, offers protection to the wearer and
does not pose a risk of getting caught up with
the object. Footwear should offer a good grip
and an appropriate level of protection.
Assuming that direct contact with an object is
necessary, then the decision as to whether
gloves should be worn or not can be made
on the basis of the likely advantages and
disadvantages of wearing or not wearing them,
bearing in mind the risks outlined above. The
wearing of gloves is strongly recommended
when handling unfinished wood, lacquered
surfaces, upholstery textiles, metal furniture
and hardware. Different gloves are available
for different purposes. Plain cotton gloves, for
general purposes, do not provide a secure grip
and may cause snagging. They provide only a
partial barrier to the effects of moisture and
salts. Most vinyl and rubber gloves provide
very secure grip and an excellent barrier to
moisture and salts but the heavier ones may
reduce sensitivity to an unacceptable degree.
These gloves are uncomfortable to wear for
long periods. Risk of snagging with the surgical
type is minimal but many people find them
uncomfortable to wear. At the cost of some
additional loss in sensitivity, they can be made
more comfortable by wearing a thin cotton or
silk pair underneath. The advantages of
wearing gloves are only obtained if the gloves
themselves are clean and in good condition.
If gloves are not worn then hands should be
clean.
Forces applied to objects (lifting, moving
and placing)
Before moving an object, it is important to
think about the method of lifting it. This will
be influenced by the nature of the surface,
type of structure, centre of gravity and weight.
A few principles intelligently applied can help
to reduce the risk of damage. Most structures
are designed to withstand forces of compression
rather than tension. Many materials are
weaker in tension than in compression. Most
furniture objects are not designed to withstand
the tension caused by lifting or the sideways
force necessary to move the object from one
place to another. A golden rule is to never put
a point of weakness under tension. Furniture
objects are normally best lifted from their
lowest load-bearing member. Holding objects
at the top will put them under tension and
may open up cracks. Similarly, the use of
protrusions as handles carries a high risk of
damage because there is a point of weakness
where the protrusion meets the main body of
the object and leverage will put this point of
weakness under tension. A joined wooden
chair, for example, is usually lifted from the
lower edge of the seat rail, never by the arms,
unless covered in deep fringing in which case
it is better to hold it by the legs. Maximizing
the area of contact will help to reduce the
pressure on the surface. Pressure = force/unit
area and therefore increases as the area of
contact becomes less. The centre of gravity of
a supported object should be on an axis vertically
above its base. A high centre of gravity
or a narrow base mean that a small tilt could
make the object unstable. If an object is
suspended it will slip until its centre of gravity
is vertically under the point of suspension.
Movement of objects is best done slowly. The
more force used the faster an object will move
or deform. If the speed of an object doubles
the amount of damage that could occur
quadruples. A weak force at the end of a long
lever can do as much damage as a strong
force at the end of a short lever. Detachable
parts should be secured or treated separately.
The weight of an object can be estimated by
treating it as a collection of boxes or cylinders.
The total volume of boxes or cylinders multi-