Hatchfield, 2014: MINIMIZING DAMAGE IN STORAGE AND DISPLAY
INTRODUCTION
artifacts, including flints, were reorganized and
stored in newly prepared cabinets. Soon after
To those working in cultural institutions, the
the rehousing, an odd and very distinctly blue
extent
to
which
environmental
factors
color was observed on some of the flints
determine the health and longevity of collection
(Abbot, 2010, figure 1).
materials is no longer a surprise. In the 1920s,
This strange phenomenon created a furor in the
Alfred Lucas, an analytical chemist working
national and international news, resulting in a
with archeologists in Egypt noted the effects of
petition to the Italian Minister of Culture to
changing environments on the objects he
identify the source of the problem, assign
excavated with archeologists like Howard
blame and provide punitive action for "severe
Carter (Lucas, 1924: 45). Pliny, writing in the
chemical
contamination
of
archaeological
first century AD noted the corrosion of lead
material, causing irreversible alteration to the
caused by vapors from roof timbers
(in
archaeological materials with enormous loss of
Rackham, 1968). Damage from soot, sulfur
scientific information and to the National
dioxide and acids seen on paintings and shell
Patrimony" (Drahl, 2010: 32-33). In 2010,
collections was documented as early as the 19th
samples analyzed at the University of Padua
century (Eastlake et al., 1850; Kenyon, 1897).
found that the surfaces showed pervasive
By 1971, the first review of damage from
contamination by various hydrocarbons and
volatile pollutants in storage cabinets on
plasticizers such as phthalates and BHT
collection objects had been published (FitzHugh
(butylated
hydroxytoluene;
Drahl,
2010).
and Gettens, 1971).
Traces of these substances were also found
Over time, chemical interactions between the
on bones and ceramics stored there, but no
materials of cultural heritage and light, heat (or
color alteration was visible. Most of the
cold), moisture (or lack of it), and pollutants
time, a dramatic, clearly visible alteration is
have
played
a
significant
role
in
the
not evident. However,
mechanical
and
deterioration of collections. This paper focuses
chemical alterations may have taken place
on pollutants and their effects on collections:
unnoticed,
and
lead
to
accelerated
how they interact with materials, and how to
deterioration of collection materials.
mitigate these effects as we make choices
Although work is still ongoing, chemists and
about handling, exhibition, storage and packing
geoarcheologists have identified three new
of the collections in our care. Although
pigment molecules by HPLC, which they called
sometimes
vastly
different
in
scale,
Romeo Blue, Juliet Blue, and Flint Blue. They
paleontological
materials,
natural
history
belong to the triphenylmethane dye family, an
collections, fine art and architecture alike share
old class of synthetic colorants related to
similar sensitivities to pollutants and will
bromocresol
green,
the
pH
indicator.
benefit from an informed use of stable, inert
The additive was identified as an antioxidant:
materials used in their environments. The
2,2,4-trimethyl-1,2-dihydroquinoline.
HPLC
presence of pollutants in storage or exhibition
identified the three pigments. The color
cases, together with other factors like high
change was traced to an antioxidant added to
relative humidity causes the formation of
the synthetic rubber
mats
used
in
the
unusual organic corrosion products on metals
armory
storage cabinets, which somehow
(sodium copper acetate on bronze, for
desorbed from the mats to the tools and
example), the alteration of mineral specimens
trimerized to form the blue contaminants
due to inappropriate relative humidity levels,
(Tapparo et al., 2011). Were it not for the color
the presence of sulfur or acids (Waller, 1999),
change of some of the flints,
contamination
the formation of calcium acetate on shells, also
of the archeological objects would probably
known as Byne's disease, calclacite (calcium
have escaped detection in the absence
of
acetate dichloride hydrate) on limestone (Van
thorough
scientific
analyses. According to
Tassel, 1945; FitzHugh and Gettens, 1971).
Laura Longo, the former curator of Verona's
One
particularly
dramatic
example
of
Natural History Museum, the adsorbed organic
irreversible alteration occurred a number of
compounds
could
bias
important
years ago in Verona. The Museo Civico di Storia
analytical results such as those conducted on
Naturale in Verona is known for its spectacular
Neanderthal
DNA
(Lalueza-Fox,
2007),
collection of marine fossils from Bolca quarry,
especially those obtained with techniques
as well as prehistoric lithic artifacts. In 2008,
probing extremely low amount of material
parts of the collections were moved from their
(Drahl, 2010). Clearly we need to be
original
locations
to
a
newly
restored,
extraordinarily careful about the materials used
decommissioned military Arsenal, intended to
in proximity to collection objects, and to
serve
as
the
permanent
site
for
the
understand their history when undertaking
archeological section of the museum. The lithic
preservation activities and analysis.
92
Journal of Paleontological Techniques