ИСТИНА

Winsor & Newton colour charts with swatches of the paints that the firm produced at certain time are of a great importance for technical art history and conservation science. Revealing the composition of these paints could facilitate interpretation of data acquired from paintings, get insights into mixtures used in manufactured materials of that time, and choose the right conservation and restoration treatment. The investigated in present work catalogues (Permanent Oil Colour, Permanent Water Colours and Scholastic Water Colours) contained in summary 166 shades. The perfect technique for an elemental analysis of such amount of flat samples is µ-XRF that is capable of rapid, non-invasive, sensitive identification of elements. Due to narrow X-ray beam spot size (~ 18 μm) that was generated by Rh tube and focused by polycapillary optics in spectrometer M4 Tornado Plus (Bruker Nano GmbH), we were able to also identify a composition of visible inclusions in some of the shades. In order to obtain most accurate information about major and minor components of the paints, we acquired spectra in at least three points of each shade, as well as in areas of paint losses to eliminate signal from underlying paper layers. Composition of some of the paints did not match with the expected from their name. For example, watercolour paint Naples Yellow contained no Pb, nor Sb. In the Permanent Oil Colour paint chart, shades contained a layer of ground. Signal of fluorescence from the primer varied in spectra of different samples so that subtraction of it did not bring satisfactory results. With the view to reveal the composition of the upper paint layer alone, additional analysis by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and polarized light microscopy (PLM) were made. Thus, we built a database of elemental composition of 166 paint samples produced by Winsor & Newton in 20th century and identified the composition of 28 tints and ground from Permanent Oil Colour catalogue.