Determination of Boron Content in Enamel and Grisaille Paintings from Stained-Glass Windows [Dataset]

All samples (reference glasses, replica enamels, and historical grisailles and enamels) were analyzed by LA-ICP-MS. These analyses were carried out at IRAMAT-CEB in Orléans (France). The analyses were done using a Resonetics M50E excimer laser (ArF, 193 nm) equipped with a S155 ablation cell and a Thermo Fisher Scientific ELEMENT XR mass spectrometer system. The ablations were typically carried out with a 5 mJ energy at 10 Hz pulse frequency in spot-mode and a beam diameter of 100 microns for the base glass. The enamels were typically analysed on the surface due to insufficient thickness with a beam diameter of 50 microns that was occasionally reduced down to 25 microns when saturation of the signal caused by high concentrations of transition metals occurred. A pre-ablation time of either 10 s or 20 s depending on the thickness of the sample was followed by 30 s signal acquisition, resulting in 10 mass scans. The ablated material is transported to the plasma torch by an argon/helium flow at an approximate rate of 1 L/ min for Ar and 0.65 L/min for He. The ion signals in counts-persecond are recorded for 58 isotopes (from Li to U). Standard Reference Material (NIST SRM610), as well as Corning glasses B, C, and D and APL1 (in-house standard glass), were used for external calibration, while 28Si was used as internal standard. Quantitative concentrations were calculated based on the procedures described by Gratuze, B., Blet-Lemarquand, M. & Barrandon, JN. J. Radioanal. Nucl. Chem. 247, 645–656 (2001). https://doi.org/10.1023/A:1010623703423. Precision and accuracy are reflected in the repeated measurements of reference glasses Corning A and NIST SRM612. LIBS analyses of all samples including reference glasses, replica enamels, and historical grisailles and enamels were carried out, at ambient atmospheric conditions, on the surface and in-depth (stratigraphic study) of the considered glass samples using laser excitation at 266 nm (4th harmonic of a Q-switched Nd: YAG laser (Lotis TII, LS-2147), 15 ns pulses, 1 Hz repetition rate). LIB spectra were recorded using a 0.2 m Czerny-Turner spectrograph (Andor, Shamrock Kymera-193i-A) equipped with a grating of 1800 grooves/mm (blazed at 265 nm) and coupled to a time-gated intensified charge-coupled device (ICCD) camera (Andor Technology, iStar CCD 334, 1024x1024 active pixels, 13 µm x 13 µm pixel). The ICCD detector is synchronized with the Q-Switch output electrical signal that triggers the laser pulse. The laser beam was directed to the surface of the samples by the use of mirrors at an incidence angle of 45°. Focusing with a 10 cm focal length lens allowed fluences in the range of 5–9 J/cm2 to be achieved. The shot-to-shot laser energy fluctuation was less than 10%. LIB spectra were recorded in the 240–600 nm wavelength range using a step and glow mode at intervals of 30 nm. For the stratigraphic analysis, the spectra were recorded by applying several laser pulses in the same area of the samples at 30 nm wavelength intervals centered at 285, 325, 360, 400 and 500 nm. The spectra were acquired at a 0.17 nm resolution with a gate delay and width of 200 nanoseconds and 3 microseconds, respectively. For higher wavelengths, a cut-off filter at 300 nm was placed in front of the entrance window of the spectrograph to reduce the scattered laser light and to avoid second-order diffractions. Each LIB spectrum resulted from a single signal acquisition as it provides good signal/noise ratios. An optical profilometer model Zeta-20 True color 3D from Zeta Instruments was used to perform the optical profiles on the pits produced by LIBS analyses in replica and historical samples. For profiling measurements, an x20 objective was used. The data were processed with Zeta View software during the acquisition and Gwyddion 2.67 software to select, and represent the final data.