Ivona Posedi has just started her PhD at the University of Lincoln in the UK and is currently at PIN learning about CIDOC-CRM in order to apply it to her work. Ivona is an archaeometrist and her interest lies in stained glass windows, particularly those in English cathedrals. For her thesis she will use diverse but complimentary techniques (e.g. SEM-EDS, handheld XRF, LA-ICP-MS, etc.) to obtain as much information about the glass as she can.
The determination of the chemical composition of the glass can provide information on the raw materials used which can be valuable for determining the possible origin(s) of the glassmaking workshop(s) and providing a socio-economical context, such as the confirmation of historical trade routes.
It is a well-known fact that French craftsmen and architects were heavily involved in the design and construction of Britain’s earliest cathedrals. Stained glass windows were very popular during the medieval period as they provide a means of educating the mainly illiterate church-goers about the Bible. With regard to the windows, there are many visual as well as chemical similarities between those found in the UK and cathedrals constructed during the same time period in France. Craftsmen would bring or import glass from France to use to create their religious works of art. Sadly, many fine samples were destroyed during the Reformation and dissolution of the monasteries under Henry 8th and then later by Oliver Cromwell but some fine examples are still to be found. The windows in Lincoln Cathedral seem very similar in design to those of Saint-Chappelle, Paris and those in Canterbury Cathedral to Chartres which was a main glass production in France during the Middle Ages.
Project objectives and the role of CIDOC-CRM
Currently, a variety of archaeometric techniques are used for analysing glass and the protocol for data manipulation and classification vocabulary (taxonomy) is not uniform. This makes it very difficult to make comparisons and draw upon existing data when conducting an investigation into the provenance of stained glass windows. The aim of Ivona’s research is to establish a standard protocol for determination of glass compositional groups and a standardized coded taxonomy. Recording information in a standard manner about the appearance of the samples and the archaeological/historical context, the conditions used for each instrument and the analysis results, along with storage in a free-access database system will enable all researchers to easily analyse, compare and reuse the data in a simpler and quicker manner. This requires the use of a XML schema for recording the data so CIDOC-CRM has been selected as the most appropriate one available to support Ivona’s research project.
Further information about the technical approaches
The complimentary techniques mentioned include:
- Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS) – this technique uses the interaction of X-ray excitation with a sample to result in an electromagnetic emission spectrum that allows identification of the constituent elements by the SEM since each element has a unique atomic structure.
- Handheld X-ray fluorescence (XRF) spectrometer – this device is used directly on the material, analysing the light (visible to UV) section of the emission spectrum resulting from X-ray excitation. Whilst it may not be as accurate as a full spectrum technique, it has the advantage of being non-destructive and portable, i.e. the equipment is taken to the sample.
- Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) uses a laser source to produce particles (aerosols) which are then ionized by the plasma source for analysis by the mass spectrometer. Highly accurate element and isotope results can be obtained from very small samples.