Abstract The external proton beam progressively gains more attention, particularly in connection with recent new possibilities combining non-vacuum PIXE and RBS. To identify paint layer arrangements and their elemental composition external PIXE was applied varying the incident proton energy. This technique is checked on a set of test paint layers combining pigments typically applied in the Middle Ages as well as presently. Thin surface paint has been successfully characterized by means of simultaneous external RBS complementary to PIXE. Presented as an example are depth resolved measurements on a red colored detail of the painting “14 Nothelfer” from Lucas Cranach the Elder.