Hatchfield, 2014: MINIMIZING DAMAGE IN STORAGE AND DISPLAY
environmental
testing
methods
involving
contact testing between materials and coupons
the
exposure
of
metal
coupons
which
is often conducted in addition to determine that
are
sent
back
to
the
company
direct physical contact between artifacts and
for
evaluation
(www.purafil.com/products/
construction materials will not be problematic.
monitoring/air_quality.aspx
).
Other simple environmental tests may be
done
with
a
minimum
of
expense or
Choosing
materials
for
proximity
to
equipment (Hatchfield, 2002: 46-47).
collections
TESTING MATERIALS
Although few materials considered for use in
collection environments are truly inert, the
The idea of testing every product considered
term is commonly used to refer to materials
for use may be overwhelming, but it is possible
with low VOC content, high stability and
to gain considerable insight into the nature of
longevity, and low risk of reactivity. Wood, of
materials by reviewing their product literature
course,
is
one
of
the
most
common
and Material Safety Data Sheet (MSDS) or
construction products found in collection
Safety Data Sheet (SDS). These sheets contain
construction. Some woods are extremely acidic
information about the physical characteristics,
and have been known to reduce sensitive
behavior and health risks of products (for
specimens to dust. Oak, for example, is one of
example, flammability, reactivity, toxicology
the most acidic woods available, but acid is
and spill procedures). It is important to keep in
released from many woods, in varying
mind that the information relates primarily to
quantities over time, and depending on many
health and safety, not to interactions with
variables including time of year the wood was
materials. For example, many materials giving
cut, where in the trunk the wood is harvested,
off acidic vapors might not be considered a
drying and preparation procedures and length
health risk, but might very well damage
of storage prior to use. Published pH levels of
sensitive materials. Nevertheless, examination
woods vary greatly and do not necessarily
of the product literature and SDS will reveal
relate to volatile acidity (Hatchfield, 2002: 67-
information allowing identification of certain
70). Once combined with adhesives and
classes of materials known to be problematic,
additives in processed wood products such as
such as alkyd resin paints or plasticized
particleboard or plywood, acidity may also vary
polyvinyl chloride. Even in cases where the
depending on the nature of those additives. In
MSDS indicates a safe material, products must
general though, wood products intended for
be tested to be certain harmful compounds are
exterior use tend to be more stable and have
not present.
lower volatile components from adhesive
The damaging effects of pollutants may be
content.
Some
products
marketed
as
caused by volatile compounds such as acidic
"formaldehyde free" will still evolve significant
gases,
semi-volatile compounds
such
as
acid and other compounds, because wood
plasticizers, or non-volatile components such as
particles and adhesives are still present.
fire retardants in fabrics, which may only pose
In areas where good air exchange exists, such
problems through direct contact with objects or
as open gallery space, the use of such wood
specimens. A range of spot tests are simple to
products is less problematic than in enclosed
conduct; however, these typically test for very
areas such as storage or display. Although
specific compounds such as sulfur, chlorine,
commercially available coating materials seem
cellulose nitrate or acetate (Hatchfield, 2002:
an attractive choice to solve the problem of
45-54). The benefit to these tests is that
pollutant outgassing from wood products, there
results are immediately obtained. A more
is no commercial product available that will
generalized test done in many museums today
prevent the evolution of acids and other
is an accelerated aging test known as the
pollutants from wood. Products developed for
modified "Oddy Test", requiring exposure of
sealing wood are intended to protect the wood
cleaned, degreased coupons of lead, copper
itself, not necessarily to prevent evolution of
and silver with individual samples under
volatile material. Numerous possibilities exist,
specific conditions at elevated temperature and
however, to prevent pollutants from emanating
relative humidity for 28 days. These coupons
inside exhibition cases. A solid vapor barrier
are compared visually to a control set of metals
such as an aluminized film can be heat sealed
which were exposed under identical conditions,
on to all wood surfaces exposed to the interior
but without the test material in question
of the case. Non-wood products such as
(Thickett and Lee, 2004). These tests are
acrylic, glass, polyvinyl ethylene or aluminum-
typically done without the metals in direct
faced construction panels can be used in place
contact with test materials; however, direct
of wood. Fabrics, gaskets, mounting materials,
95
Journal of Paleontological Techniques