In the case of more complex works, during restoration, and whenever a complete description of the painting technique, provenance determination, or authentication of the work is required, non-invasive research alone is usually insufficient. However, if it is carried out, the necessary sampling can be significantly streamlined and reduced. It is generally more gentle and beneficial to take fewer samples from well-chosen locations than to take samples randomly or from defects where sampling is possible but the stratigraphy of the layers is disturbed. Describing the stratigraphy of the paint layers is the first step in the examination of micro-samples in the laboratory. Individual chronologically distinguishable interventions are described, and thus both the original painting and overpaintings are interpreted.

Analyses of the micro-samples taken include the identification of pigments, binders, and substrate materials, using appropriate microscopic (optical and electron microscopy with EDS analysis), spectroscopic (infrared and Raman spectroscopy), and diffraction (powder X-ray diffraction) methods. To solve special tasks and wherever its own equipment is insufficient, the laboratory has established a network of collaborators within and outside the Academy of Sciences so that it is always able to provide comprehensive conclusions. Special tasks include, for example, the analysis of trace elements, the specification of protein binders, or radiocarbon dating of the substrate (wood, canvas).

More detailed analyses, carried out in a targeted manner, can then answer questions about the origin of the work (regional provenance/place of origin, dating, authorship, workshop affiliation). The basis for these advanced interpretations at the ALMA laboratory is comparative research, which is based on experience gained during 25 years of analyzing works from different periods and provenances. The research combines analyses using state-of-the-art equipment with comprehensive knowledge of painting techniques and materials used in the visual arts. The research possibilities are constantly updated according to the results of the laboratory's own experimental research.

The collection of micro-samples from a Gothic panel painting. © ALMA Laboratory