When I first saw the painting of an Elizabethan woman — thought possibly to be a portrait of Queen Elizabeth I herself — it was split completely down the middle, with paint flakes hanging off like an outcrop and its two halves curved like a shield. The heating system in the National Trust-owned house in the UK where it was on display behaved erratically in the winter, and the relative humidity had dropped dramatically. The 5 mm thick painted wood panel responded by warping so severely that its frame eventually restrained it, forcing the panel to crack under the pressure.

Conservators and conservation scientists play a key role in physically preserving important parts of our cultural heritage. With the Elizabethan painting, our team’s remit here at the Courtauld Institute of Art in London was to repair the split, find out more about the painting’s provenance, understand its environmental response and provide a suitable mount to protect it from future damage. To do this, we carefully realigned the two halves of the panel and rejoined them with a polyvinyl-acetate adhesive, taking care not to lose the flakes of paint clinging precariously to each side. A surface fill of chalk and gelatine covered the join, which was then retouched using a hydrocarbon compound and dry pigments, before finally being varnished.

We monitored the movement of the panel by simply marking out its profile on graph paper and found it responded almost immediately to small changes (5%) in relative humidity. We were able to slow down this response by applying a coating of ethylene vinyl acetate to the back of the painting, building a flexible support for it and placing it in a sealed, glazed frame. It has now been returned to Trerice in Cornwall, where it is again on display.

Bringing art and physics together

I was first attracted to conservation science by the opportunity to work hands-on with fascinating and often beautiful objects of cultural heritage — each presenting a plethora of interesting and demanding problems for scientists as well as art historians or curators. The complexity and individuality of each object requires us to understand and integrate ideas from many fields. To conserve an object, many different factors must be considered, including its aesthetic, provenance and history; the artist’s intent, choice of materials and original technique; and the object’s physical condition.

I studied both art and science at A-level, and I always assumed they were facets of the same universe. I chose to study physics at Imperial College London because I liked the philosophical as well as the mathematical aspects of the subject. After I finished my undergraduate degree, I decided to do a Master’s degree in applied optics at Reading University because it brought together many of my interests, from the theory of colour and vision to the creativity of designing experiments and specialized lenses.

After I left university and started working on optical-systems design at the Rutherford Appleton Laboratory and then at Chelsea Instruments, I saw an advert for a postgraduate conservation course, and really became aware that I could combine science and art. However, funding was not available at the time so instead I started a PhD in mechanical engineering at Imperial, researching techniques used to look for defects in ceramic tiles. I then realized these same techniques could be applied to non-destructive testing of works of art, so I contacted the scientific departments of the National Gallery in London and the Tate to find out more about the problems encountered in paintings. Seeing the work they did made me decide that this was the area I wanted to work in, so I persuaded my supervisor to let me change my PhD topic to cover the physical properties of canvas paintings.

I soon found out that there are numerous ways in which to apply my physics knowledge to this field. For the past 16 years I have been using a technique called electronic speckle pattern interferometry, which employs lasers and interferometric imaging to measure the strain induced in paintings. I have also experimented with other methods like pulsed thermography and infrared optical coherence tomography to identify subsurface features and adhesion between layers in works of art, and used multispectral imaging to understand artists’ materials and techniques.

Patterns at work

I joined The Courtauld, which consists of the Courtauld Gallery and the Institute of Art, in 2000. The Gallery houses a famous collection of Impressionist and Post-Impressionist paintings (including works by Manet, Monet, Cezanne and Renoir) and the Institute of Art is a college of the University of London that specializes in art history and conservation. My research interest is in non-invasive techniques for measuring the physical condition of paintings, and developing methods for structural conservation treatments.

Working within an academic environment means that the flow of students, lectures and exams provides an overall structure to the year, but beyond that my day-to-day activities vary quite a lot. Our postgraduate students treat paintings starting in their first year, which requires a lot of studio supervision. So on an average afternoon, I might be recording an infrared image to check for any drawings underneath the paint, using ultraviolet light to identify retouching and varnish, or using a technique called energy-dispersive X-ray spectroscopy (EDX) to identify chemical elements in the paint layers. Equally, I could be removing a painting from its wooden support, mending tears, designing a mount for a panel painting, or undertaking an environmental survey at a historic house where paintings — like the Elizabethan portrait — are displayed.

Careers in conservation

Conservation science is a relatively small field, and there is a lot of collaboration between institutions and individuals. In general, paintings conservators work directly on an object; so depending on what is required, they may remove a degraded varnish, repair a tear in the canvas, fill and retouch where paint has flaked off, or, as with the Elizabethan painting, rejoin a wooden panel that has split. Conservation scientists, in contrast, usually take a more indirect approach. For example, we may analyse paintings using X-rays (see “Underneath the surface”), monitor the movement of a painting due to environmental changes with optical or mechanical techniques, or use small original samples or replicas to investigate new cleaning methods in a laboratory setting.

Research and practice are more closely interrelated than in many scientific fields, which makes the work very satisfying. I keep abreast of emerging techniques in applied physics and engineering, and I have longterm collaborations with conservators, scientists and engineers from several institutions, including the National Physical Laboratory, Imperial College London, the Tate and National galleries and the Museum of Modern Art (MoMA) in New York.

For a physicist, there are many ways to work in the field either as a conservator or as a conservation scientist, or as both. The principal employers of conservation scientists are the scientific departments or preventive conservation sections of major museums and public collections in Europe and the US. Many come into the profession as I did, through doing a PhD at a university with external links with a museum. Scientists are sometimes employed at a junior level directly after completing undergraduate or postgraduate courses, without prior training in a conservation-related field; they then learn on the job.

There are also sometimes research-assistant posts in conservation-science research projects. At The Courtauld, we have recently had two projects: one investigating artists’ materials and techniques using microscopy, Raman spectroscopy and EDX spectroscopy; the other working with ultraviolet lasers to investigate their suitability for cleaning 19th-century paintings.

For those wanting to work hands-on with objects as conservators, then a postgraduate training course is the recognized route. There are two- and three-year postgraduate courses available in many areas — including easel paintings, wall paintings, paper, objects, stained glass, preventive conservation and archaeology — for which a first degree in physics is appropriate. Usually, after finishing their postgraduate course, students work on short-term contracts to build up experience. Conservators are employed in museums and galleries or work privately in many countries. Finding permanent posts at institutions is more difficult, but most conservation-trained scientists do eventually find full-time work.

For those wanting to see if conservation might be for them, a good start would be to read the technical bulletins published by the National Gallery, British Museum or similar institutions outside the UK. Several museums and galleries also maintain good conservation webpages, and two conservation-community websites, icon.org.uk and iiconservation.org, contain a number of useful resources. The most important step, however, is to go to museums, galleries and cultural-heritage sites to look at things and find out what really interests you.