In situ study of Limoges painted enamels by portable X-ray fluorescence supported by laser ablation inductively coupled plasma mass spectrometry analysis of micro-samples

Portable XRF (X-ray fluorescence spectrometry) was used during non-invasive measurements of Limoges enamels from the collection of the National Museum in Warsaw (Poland). Four tiny micro-samples with dimensions below 1 mm2 were collected from 3 objects and subjected to multi-elemental LA-ICP-MS (Laser Ablation Inductively Coupled Plasma Mass Spectrometry) investigations, including oxides quantification and data imaging approach. Comparison of the obtained LA-ICP-MS data and literature glass compositional information allowed for possible dating of the investigated plaques to 16th or the first half of 17th century. The XRF spectra revealed the unexpected presence of Pt in one of the analyzed objects within areas of evident intervention/restoration recognized by a conservator. These results were confirmed by LA-ICP-MS imaging of a tiny silvery foil fragment sampled from the restoration inserts. Probably the first or one of the first examples of identification of Pt foil in a repair on a Limoges enamel restoration is reported in this work.