After attending a series of workshops for conservators on an innovative X-ray technique at the invitation of her former students, it was clear to Maggi Loubser, Head of the University of Pretoria’s (UP) Tangible Heritage Programme, that there was a need for a workbook on the subject that students could use as a training resource.

Loubser has now jointly published a book titled Handheld XRF in Cultural Heritage: A Practical Workbook for Conservators with colleagues at Yale University and the Getty Conservation Institute

The analytical chemist by training has 17 years of industry experience during which she learnt X-ray fluorescence (XRF) spectroscopy. She also ran an XRF facility at UP for 15 years. This method is widely used in mining and manufacturing for ore estimation and process control, but over the past few years it has been used by conservators on art and heritage materials.

“It gives us information regarding the material used by the artist, which in turn enables us to decide on the correct conservation treatments,” says Loubser. “When for instance, you want to remove old discoloured varnish from a painting, you need to know your solvents will not dissolve the pigments used in the paint. When a sculpture suddenly starts corroding, XRF analysis can identify what the resulting corrosion product is and decide what caused it, like an incompatible solder or a patination process that was done with the wrong chemical.”

She explains that XRF spectroscopy “is an analytical method where we use X-rays (just like medical X-rays) to excite the atoms in a sample. The sample can be almost any solid; a soil, metal, polymer, painting or sculpture. When the excited atoms relax to their ground state, they give off X-ray photons from which the energy tells us exactly what element in the periodic table generated the photon and the intensity tells us how many of those specific elements were present in the sample.” 

Maggi Loubser at work.

She said when she analysed a painting attributed to Rembrandt in the University’s Van Tilburg collection and found lithopone (a barium and zinc pigment), and not nearly as much lead pigment as was expected, “it was clear that this could not have been a Rembrandt painting, as lithopone was only in use from 1850 onwards, long after the 1640s when Rembrandt supposedly painted this work”.

The book is the first of its kind and should have been launched at the American Institute for Conservation Annual Meeting, but took place online, due to the lockdown as a result of COVID-19.

The idea for the book was sparked by XRF Boot Camps held at Yale University, Getty Museum in Los Angeles and Maastricht, Netherlands, after two of Loubser’s former students, Aniko Bezur and Lynn Lee, approached her in 2013 to be part of an XRF Boot Camp for Conservators. “It was clear from these training workshops that a workbook that students could use as a training resource would be immensely valuable.”

The book starts with a chapter on safe operation of X-rays followed by a chapter on the fundamental principles of the technique, written in language accessible to non-scientists.  The third chapter consists of practical exercises that can be undertaken which elucidate the theoretical principles. The fourth chapter covers the practical applications of XRF to cultural heritage materials and how to interpret and report data.

Loubser explains that with the current international emphasis on decolonisation and restitution, it is clear that cultural heritage objects removed from Africa during colonial times need to return to their rightful home. However, in Sub-Saharan Africa the skills and facilities to care for heritage objects are scarce and there are no academic programmes for training. Most practising conservators in South Africa have been trained in Europe, in a previous generation. “Their knowledge has been disseminated to interns, who became very capable artisans themselves, but methods and techniques have advanced over the past decades and through isolation we may have fallen behind regarding developments in the latest conservation practices.  There is a serious lack in training opportunities for both practising and prospective conservators, and no centre to serve as hub for research and development.”

Referring to UP’s Tangible Heritage Programme, which was started in 2019, and which includes XRF conservation techniques as part of the programme, Loubser says “we hope our students will head into the world as advocates for conservation, helping people at every level – from local communities to the decision makers in government institutions – to understand the significance and urgency of caring for our heritage.”