TESTING AND TRIAL LASER CLEANING OF A POLYCHROMED STONE SCULPTURE FROM THE COLLECTION OF THE POZNAŃ NATIONAL MUSEUM (MNP)

TESTING AND TRIAL LASER CLEANING OF A POLYCHROMED STONE SCULPTURE FROM THE COLLECTION OF THE POZNAŃ NATIONAL MUSEUM (MNP)

Toruń, November 2017

The collection of MNP includes a medieval stone sculpture representing the head of an unidentified holy woman. It was purchased by Izabella Czartoryska for her private collection. Its provenance remains unknown. Its style and features suggest that it may have been made by a French atelier.

Our lab was given the task of conducting laser cleaning tests on the sculpture.  Given its many coatings, including traces of polychromy and gilding, it was first examined using XFR to determine the composition of the preserved layers of paint. As a result, elements were identified which indicated the presence of historical pigments, e.g. azurite, malachite or iron-containing earth pigments, including some sensitive to laser radiation, i.e. white lead or cinnabar.  Therefore, the trials had to be limited only to designated small areas. Good results were achieved for raw stone surface when applying laser beam with a wavelength of 532 nm.

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