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Science in Art:
A chemical engineer’s journey through art conservation
Seven years ago, soon after I’d
graduated from Imperial, I packed
my bags and left the UK for a
PhD in the States. Enrolled as
a postgraduate student in the
Chemical Engineering department
at Princeton, I anticipated a future
career in oil and gas, pharmaceuticals,
consumer goods, or something
else within my known realms of
chemical engineering. So I was quite
surprised when I found myself one
day sitting in an engineering class
and learning about art conservation.
The course, titled “Introduction to Materials
Science” had been advertised as a postgraduate
cross-disciplinary elective for engineers. “But
what does art conservation have to do with
materials science or chemical engineering?”
I’d wondered. Curious to find out, I made an
appointment with the professor, a joint faculty
member in the Civil Engineering, Chemical
Engineering and Mechanical and Aerospace
Engineering departments, and amongst
whose research interests, I soon discovered,
was art conservation. Little did I know that
that meeting would mark the start of my
own research and that six years later, I’d be
in a position to talk about conservation with
others.
Art conservation, in a nutshell, is the
preservation of objects and structures
that possess cultural heritage value from
environmentally induced deterioration. The
objects themselves can range from porcelain
to paintings, books to textiles and statues
to monuments. There are, for example,
conservators working on the restoration of
Japanese bronze statues, others that work on
restoring wood panel paintings and others
still that treat old sandstone castles to prevent
salt crystallisation. In this field, scientists and
engineers make up only one part of a team
that also includes art historians, archaeologists,
artists and museum curators. The scientist’s
role is to study the properties of the materials
and the deterioration processes that they
undergo, and to develop ways of protecting
and restoring the materials. The work can be
in the form of prevention, whereby the cause
of damage is addressed before deterioration
occurs, or in the form of treatment, whereby
deterioration that has already occurred is
mitigated.
The lab I worked in, during my PhD,
studies stone conservation. Stones such as
marble and limestone are composed of the
mineral calcite, and have been important
materials in art and construction for centuries.
Unfortunately, however, stones are susceptible
to weathering in the outdoors. Limestone
is porous and is thus vulnerable to a host of
environmental processes, such as freeze-thaw
cycles, salt crystallisation in its pores and acid
attack, which all cause the stone to weaken.
Marble, on the other hand, is almost nonporous
and therefore much less vulnerable
to most forms of weathering, but is still
susceptible to acid attack on its surface. Since
the onset of industrialisation, acid rain has
been a major environmental issue, with some
of the most polluted cities in the world being
home to many of our most valued marble
structures, such as the Taj Mahal (Agra) and
the Parthenon (Athens). Marble is susceptible
to dissolving in rain because calcite is
extremely soluble in acid. At the pH of normal
rainwater (pH 5.6), it will dissolve at a rate of
about 1.2 mm per century, assuming rainfall
occurs 1% of the time. If the pH decreases
to 4.6, which is not unrealistic in many
urban areas, the dissolution rate becomes
1.2 cm per century – all it would take are a
© Sonia Naidu
Image of a marble statue inside the conservation workshop at the Palace of Versailles.
Damage caused by exposure to the elements can be seen in the form of cracks, stains and acid etch marks on its surface.
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Imperial ENGINEER Spring 2015