The ALMA Laboratory conducts customised surveys of paintings, which include non-invasive measurement of the entire object, analysis of micro-samples taken, and interpretation of the painting technique. Non-invasive research (without sampling, contactless, and in some cases without the need to transport the work) can be carried out either independently (for example, as part of art-historical research, without any connection to the restoration of the work) or as the first, often necessary, phase preceding sampling (so-called screening). The inclusion of material research in art-historical projects and the participation of material scientists is an important innovation in practice and allows both research approaches to be combined directly. Non-invasive analysis of works is a current trend in the field, and the amount of information that can be obtained in this way is growing rapidly.
The basis of non-invasive research at the ALMA Laboratory is X-ray fluorescence analysis of elemental composition, using both portable devices and a large-area X-ray fluorescence (MA-XRF) scanner. The output of X-ray fluorescence scanning is large-area elemental maps, which are used not only to identify the pigments used, but also to visualize the internal structure of the work according to the chemistry of the colors used, to identify overpainting, and to interpret the painting technique on a micro scale. This method thus often fully replaces traditional imaging and radiography techniques, such as radiography. ALMA was the first laboratory in the Czech Republic to introduce portable XRF analyzers (since 2005 as part of an international project) and X-ray fluorescence scanning (since 2018) into the practice of examining paintings. It therefore has a wealth of experience in this field.
For the examination of works in situ, both in galleries, museums, and historical buildings, the laboratory can use a complete set of portable devices. In addition to a handheld XRF analyzer, which is very versatile, portable devices for infrared and Raman spectroscopy are also available.
The use of an MA-XRF scanner in the non-invasive examination of a Romanesque polychrome statue – a Madonna of the Sedes Sapientiae type from the Montanelli Museum in Prague. © ALMA Laboratory