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Authenticity screening of stained glass windows using optical spectroscopy

View Article: PubMed Central - PubMed

ABSTRACT

Civilized societies should safeguard their heritage as it plays an important role in community building. Moreover, past technologies often inspire new technology. Authenticity is besides conservation and restoration a key aspect in preserving our past, for example in museums when exposing showpieces. The classification of being authentic relies on an interdisciplinary approach integrating art historical and archaeological research complemented with applied research. In recent decades analytical dating tools are based on determining the raw materials used. However, the traditional applied non-portable, chemical techniques are destructive and time-consuming. Since museums oftentimes only consent to research actions which are completely non-destructive, optical spectroscopy might offer a solution. As a case-study we apply this technique on two stained glass panels for which the 14th century dating is nowadays questioned. With this research we were able to identify how simultaneous mapping of spectral signatures measured with a low cost optical spectrum analyser unveils information regarding the production period. The significance of this research extends beyond the re-dating of these panels to the 19th century as it provides an instant tool enabling immediate answering authenticity questions during the conservation process of stained glass, thereby providing the necessary data for solving deontological questions about heritage preservation.

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Related in: MedlinePlus

Spectral analysis of all blue fragments unveils three separate groups B1, B2 and B3 (the sample numbers of each group population are given in Supplementary Table 1).The first Co2+ absorption band is close to 534 nm favouring a soda-rich glass matrix.
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f2: Spectral analysis of all blue fragments unveils three separate groups B1, B2 and B3 (the sample numbers of each group population are given in Supplementary Table 1).The first Co2+ absorption band is close to 534 nm favouring a soda-rich glass matrix.

Mentions: The classification based on overall spectral shape of the spectra belonging to the blue panes leads to three groups B1–3 (Fig. 2). Maximum transmission occurs between 350–500 nm; the three groups differ in spectral position of the transmission maximum with averaged values of respectively 456.0 (±1.4), 459.6 (±1.7) and 393.0 (±1.4) nm. Analysis of the absorbance spectra indicate the presence of cobalt as colouring element. Cobalt is characterised by the presence of three successive absorption bands close to 535 nm, 596 nm and 640 nm attributed to the Jahn-Teller split transition A2 → T1(P) of Co2+ tetrahedral coordinated by four oxygen ions25. In all spectra of the blue fragments these bands are visible. Apparent is the common spectral position of the first cobalt absorption band of all blue fragments close to 534.2 nm (±1.6). Ceglia et al. correlates the spectral shift of this band to the composition of the historical glass26. Glasses with a calco-potassic composition have a band situated around 526.5 nm (±1.5 nm) shifting towards longer wavelengths (535 nm ±2 nm) in case of a soda based composition. These observations correspond with those made by Green and Hart27. Therefore, we conclude that the blue panes contain cobalt as colouring agent in a soda containing glass matrix and thus we can exclude a 14th–15th century origin.


Authenticity screening of stained glass windows using optical spectroscopy
Spectral analysis of all blue fragments unveils three separate groups B1, B2 and B3 (the sample numbers of each group population are given in Supplementary Table 1).The first Co2+ absorption band is close to 534 nm favouring a soda-rich glass matrix.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5121600&req=5

f2: Spectral analysis of all blue fragments unveils three separate groups B1, B2 and B3 (the sample numbers of each group population are given in Supplementary Table 1).The first Co2+ absorption band is close to 534 nm favouring a soda-rich glass matrix.
Mentions: The classification based on overall spectral shape of the spectra belonging to the blue panes leads to three groups B1–3 (Fig. 2). Maximum transmission occurs between 350–500 nm; the three groups differ in spectral position of the transmission maximum with averaged values of respectively 456.0 (±1.4), 459.6 (±1.7) and 393.0 (±1.4) nm. Analysis of the absorbance spectra indicate the presence of cobalt as colouring element. Cobalt is characterised by the presence of three successive absorption bands close to 535 nm, 596 nm and 640 nm attributed to the Jahn-Teller split transition A2 → T1(P) of Co2+ tetrahedral coordinated by four oxygen ions25. In all spectra of the blue fragments these bands are visible. Apparent is the common spectral position of the first cobalt absorption band of all blue fragments close to 534.2 nm (±1.6). Ceglia et al. correlates the spectral shift of this band to the composition of the historical glass26. Glasses with a calco-potassic composition have a band situated around 526.5 nm (±1.5 nm) shifting towards longer wavelengths (535 nm ±2 nm) in case of a soda based composition. These observations correspond with those made by Green and Hart27. Therefore, we conclude that the blue panes contain cobalt as colouring agent in a soda containing glass matrix and thus we can exclude a 14th–15th century origin.

View Article: PubMed Central - PubMed

ABSTRACT

Civilized societies should safeguard their heritage as it plays an important role in community building. Moreover, past technologies often inspire new technology. Authenticity is besides conservation and restoration a key aspect in preserving our past, for example in museums when exposing showpieces. The classification of being authentic relies on an interdisciplinary approach integrating art historical and archaeological research complemented with applied research. In recent decades analytical dating tools are based on determining the raw materials used. However, the traditional applied non-portable, chemical techniques are destructive and time-consuming. Since museums oftentimes only consent to research actions which are completely non-destructive, optical spectroscopy might offer a solution. As a case-study we apply this technique on two stained glass panels for which the 14th century dating is nowadays questioned. With this research we were able to identify how simultaneous mapping of spectral signatures measured with a low cost optical spectrum analyser unveils information regarding the production period. The significance of this research extends beyond the re-dating of these panels to the 19th century as it provides an instant tool enabling immediate answering authenticity questions during the conservation process of stained glass, thereby providing the necessary data for solving deontological questions about heritage preservation.

No MeSH data available.


Related in: MedlinePlus