In the last year of his studies, Pavol Sás restored a polychromed sculpture and, with his colleague, a large-dimensional altarpiece panel with The Last Judgement. The intervention in the latter case consisted of an exigent removal of the surface yolk overpainting, the glue consolidation, and the layers of degraded varnish with impurities. The most exacting part of the process was removing the secondary oil overpainting, which resulted in a completely different character of the work. The theoretical section of the diploma pursues multispectral imaging methods in the field of non-invasive research. Sás produced an array of pattern books of pigments found on various supports with various binding agents and documented them via multispectral photographs.