XRF Internship at St Cecilia’s Hall

In this week’s blog, we hear from Despoina Papazoglou who was an intern at St Celilia’s Hall from April to June 2019. Her internship focused on the material analysis of a painted 17th-century harpsichord using XRF…. 

Hello! My name is Despoina and I decided to write this article to share my experience of an eight-week journey as an intern at St Cecilia’s Hall. This is the first time I have written something for a blog, so before I started I googled “how to write my first blog?”, and seriously, I couldn’t understand a thing…just for a moment, I believed that quantum physics was easier to understand!

Let’s start with when I found the vacancy for the internship. The title “Scientific Material Analysis of Musical Instruments Internship” sparked curiosity within me as my professional background is in the field of material science. After reading and re-reading the job description I knew I wanted to be part of the project, as I realised it would not only expand my knowledge but also expose me to new challenges that would help me achieve my future career goals. I was so excited about the job and wanted to be part of it so badly that I did extensive research and learnt all about the museum and the collections displayed within it. Long story short, I sent in my CV, attended the interview and was offered the internship. I was probably the happiest person on earth! One of my biggest desires came true, and I could finally work in a museum with people who share the same passion as me – the conservation and preservation of cultural heritage.

The eight-week internship was full of challenges, knowledge and pleasant moments! Jonathan Santa Maria Bouquet, the Musical Instrument Conservator, and I worked on a project to identify the pigments used in the painting on the soundboard of a harpsichord made by Ioannes Couchet in 1645. After completing my radiation training (in the third week), I was able to work independently with the XRF device. We analysed every single painted motif on the soundboard to discover any similarities or differences between them. Our schedule was rigorous, as we were striving for excellence.

Two members of staff take photographs of the interior of a harpsichord.

Jonathan and Despoina carrying out XRF analysisand DP XRF

In conservation, the XRF technique is essential in the study of materials. It is one of the simplest ways to obtain information about an object without causing any damage as the device does not come in to contact with the item. The measurements can be run in situ, which means less handling and movement of large objects like the harpsichord. With XRF, pigments are identified by looking at the elements they are composed of. For example, vermilion (a bright red pigment made from the mineral cinnabar) is made primarily of Hg (mercury) and S (sulfur), while cadmium red (a pigment that produces a similar range of hues as vermilion) is composed primarily of Cd (cadmium), S (sulfur), and Se (selenium). So by looking at the characteristic elements the pigment is composed of, we can tell the difference between two red colours on a painting. The fact that several pigments have the same characteristic chemical element make the process of identification particularly complicated, and sometimes other techniques need to be employed to identify the colour.

We analysed hundreds of points on the painted harpsichord, looking at all the different colours and tonalities. Although the floral wreath which surrounds the central rose contains the whole palette used, each motif was analysed separately to examine any differences between similar colours and hues. The most frequent elements we detected were Hg (mercury), Pb (lead), Cu (copper), Fe (iron), Ar (argon) and Ca (calcium). However, in some areas Co (colbolt), Bi (bismuth), Zn (zinc), S (sulfur), Ti (titanium), K (potassium), Cl (chlorine) and Mn (manganese) were also identified.  Based on these elements it was possible to identify the pigments or at least make a hypothesis on the applied painting materials and the colour layer sequence.

Photograph of a top-down view of a harpsichord.

Ioannes Couchet’s harpsichord (1645)

We found that the pigments applied were contemporary with the period of time in which the harpsichord was made (17th century). For example, we detected lead white (identified on the spectra through the characteristic peaks of Pb), yellow and red ochres (Fe), red lead (Pb), umbra (Mn, Fe), vermilion (Hg), azurite (Cu), lead-tin yellow (Pb, Sn) and a copper-based green pigment (Cu). These pigments are mostly used in combination with others from the palette to obtain the desired shade. The highlights were carried out with lead white, applied pure or added to the primary colour, and lead-tin yellow. It is likely that an organic red and a black pigment were also used, which cannot be confirmed by XRF due to the low atomic number of characteristic chemical elements. Finally, we examined the retouched areas using XRF. We believe that organic pigments were also used in these areas as it was not possible to get any readings from them. Further analysis needs to be carried out to confirm this.

The internship was a unique experience full of challenges, and I learnt a great deal. During my time at St Cecilia’s Hall, I was able to expand my knowledge and become familiar with a new method of characterisation which is widely used in conservation. I met some wonderful people to whom I am grateful for not only being great colleagues, but friends as well. A special thanks to Jonathan whose guidance and absolute trust played a crucial role in making my journey great, which if I had the opportunity, would love to go through it again. But, unfortunately, all good things come to an end!

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