Paintings - a challenge for XRF and PIXE analysis

Conventional pigment analysis of paintings requires the removal of micro-samples followed by the preparation of cross-sections. There are also requirements for investigating several locations within a painting in order to obtain information about dating and provenance or the reason for aesthetic impressions of the paint materials. The need to carry out such work without removing samples prompted the present project, in which the authors aimed to examine the possibility of applying XRF and PIXE methods in a complementary manner. The ion beam techniques of external PIXE plus Rutherford backscattering could distinguish painting techniques, i.e. paint layer arrangements and pigment admixtures, whereas portable XRF represents a valuable tool for preselecting the objects of interest which could be transported to the ion beam laboratory. This procedure was tested using samples of prepared paint layers. It is shown that it is possible to distinguish between two or three layers. The situation would be more difficult for more complex paint layer arrangements.