Gothic green glazed tile from Malbork Castle: multi-analytical study
Looking at the façade of a historical building, it is often difficult to distinguish between the original decoration and later additions. One such building is the Holy Virgin Mary Church at the Malbork Castle (Northern Poland), built between 1276 and 1406. During the latest restoration works, ceramic tiles with some remnants of the green glaze, decorating the Holy Virgin Mary Church façade, were studied in situ using portable X-ray fluorescence spectrometry. Micro-samples were analyzed in laboratory by scanning electron microscopy with energy dispersive X-ray spectrometry (SEM–EDS) and wavelength-dispersive X-ray spectrometry (SEM–WDS), micro-Raman spectroscopy and powder X-ray micro-diffraction. We found that what was originally thought to be a paint layer was in fact a heavily deteriorated SiO2–PbO glaze. White, yellow and black pigments were found to have been added into the glaze as opacifiers and colorants. Copper and iron were used as glaze colorants. The originally added pigments were transformed into new phases, such as antimony-doped tin oxide. The technology used to produce the glazed tiles was identified. All the results collectively confirmed the medieval origin of the green glazed tiles.Graphical abstractGothic green glazed tile from Malbork Castle: multi-analytical study.
The examination of Van Gogh’s chrome yellow pigments in ‘Field with Irises near Arles’ using quantitative SEM–WDX
In this paper we present the results of quantitative measurements on the pigment chrome yellow (PbCr1−xSxO4 with 0 ≤ x ≤ 0.8) using scanning electron microscopy-wavelength dispersive X-ray analysis (SEM–WDX). Traditionally, Optical Microscopy (OM) in combination with scanning electron microscopy-energy dispersive X-ray analysis (SEM–EDX) is used for the identification of many pigments in paint cross-sections based on their particle characteristics and elemental composition. However, in the case of chrome yellow, the lead (Pb) and sulphur (S) peaks overlap, which makes quantitative analysis unreliable. SEM–WDX does not suffer from this problem and we have demonstrated that this technique can distinguish different types of chrome yellow based on the quantification of the sulphur-content of the pigment. This identification can be performed on paint cross-sections, allowing for distinction between chrome yellows in different paint layers. In addition, our study showed that the different types of chrome yellow can still be identified even in low concentrations. Van Gogh made wide use of different hues of chrome yellow. Using this method, we have identified the types of chrome yellow he used in Field with Irises near Arles, which we have been able to correlate with the information in his letters. Raman spectroscopy of the same samples confirmed the SEM–WDX results, but evidenced a higher sensitivity of the latter technique in revealing small amounts of sulphur-rich PbCr1−xSxO4 in mixtures with PbCrO4. SEM–WDX is also more accurate, because it allows the lead(II) sulphate fraction to be determined within 1 mol% absolute, whereas with Raman spectroscopy only relatively broad ranges can be defined. The on-going research of Van Gogh’s paintings as part of a cataloguing project—a collaboration between the Van Gogh Museum, the Cultural Heritage Agency of the Netherlands and Shell—opens the way for a comprehensive comparison of the chrome yellows used by Van Gogh using SEM–WDX.
Annual Reports
Links [1] https://isc.idaho.gov/annual2015 [2] http://www.isc.idaho.gov/annual2014 [3] http://www.isc.idaho.gov/annual2013 [4] https://isc.idaho.gov/../annual2012 [5] https://isc.idaho.gov/../annual2011 [6] https://isc.idaho.gov/../annual2010 [7] https://isc.idaho.gov/../annual2009 [8] https://isc.idaho.gov/../annual2008 [9] https://isc.idaho.gov/../annual2007 [10] https://isc.idaho.gov/../annual2006 [11] https://isc.idaho.gov/../annual2005