The ancient stained windows by Nicolò di Pietro Gerini in Florence. A novel diagnostic tool for non-invasive in situ diagnosis

Materials and technological evolution of ancient cobalt-blue-decorated ceramics: Pigments and work patterns in tin-glazed objects from Aragon (Spain) from the 15th to the 18th century AD

“…9) that distinguishes this group from under-glaze decorations. A peak at 480 nm and shoulders at 443 and 457 nm have also been observed in pure deep cobalt blue (or Thénard's blue from Zecchi) and blue glasses, respectively, 33 a shoulder at 440 nm in blue windows panes 34 and at circa 430 nm in blue-decorated majolica. 6 This shoulder could be compatible with the presence of Fe(III), as reported by some authors, 34 because the quantity of this element solved from the pigment can be higher when the decoration is applied on the glaze surface (1-2 wt% Fe 2 O 3 ).…”

“…38 The peaks appear slightly red-shifted compared to those expected, like other potash glasses and smalt pigments, thus indicating a smaller ligand field strength in the presence of potassium. 33,34 Moreover of these characteristic bands, common to all samples, only absorbance spectra of on-glaze decorations showed a slight shoulder at 450 nm ( Fig. 9) that distinguishes this group from under-glaze decorations.…”

“…33 However, several studies on cobalt in similar amorphous glass phases have demonstrated that this element is in the form of high-spin Co(II) ion in a tetrahedral (or pseudo-tetrahedral) coordination in the glassy matrix. 6,[33][34][35][36] The three signals have to be attributed to the Jahn-Teller splitting of the A 2 → T 1 (P) bands because of the distortion of the tetrahedral structure 37 or to an interaction between L and S quantic numbers. 38 The peaks appear slightly red-shifted compared to those expected, like other potash glasses and smalt pigments, thus indicating a smaller ligand field strength in the presence of potassium.…”

Florence baptistery: chemical and mineralogical investigation of glass mosaic tesserae

“…The ion Co(II) has been detected also in purple tesserae (BF15, BF19, BF30) where the main chromophore is Mn(III), which is usually characterized by an absorption in the interval 450e500 nm (Bamford, 1977;Bacci et al, 2007) (Fig. 8, see BF19).…”

Optical spectroscopy as a rapid and low-cost tool for the first-line analysis of glass artefacts: a step-by-step plan for Roman green glass

“…In all the articles mentioned above, the optical spectrometers were quite bulky (and expensive). The state of the art, present day commercially available portable spectrometers have only been used for the in-situ characterization of figurative stained windows (Bacci et al, 2007).…”