A XANES study of chromophores: the case of black glass

Abstract

In the 1st–2nd century AD, glass was made black using strongly reducing conditions. Later, the black appearance was obtained adding an excess of colourant rather than controlling the furnace atmosphere.

Towards refining the classification of glass trade beads imported into Southern Africa from the 8th to the 16th century AD

“…The Raman spectrum of glass consists of two broad bands, one around 500 cm -1 (SiO 4 bending vibrations), and one around 1000 cm -1 (SiO 4 stretching vibrations). Previous studies on glass and glass beads [4,[11][12][13][14][15][16] ak maxima from this s taining only ed in Fig. 4 seen in Fig.…”

Spectroscopic Investigation of the Coloration and Fabrication Conditions of Medieval Blue Glasses

“…Data from this study 13‐1: ◯; 13‐2: ▵; 13‐3: ◇; 13‐4: ◻ as original (black plain symbols). Data from previous studies are reported: ❋, ×, ⧖, ▽, black symbols: blue and blue‐green glasses, gray symbols: other colors. Three domains (i), (ii) and (iii) are distinguished (see discussion).…”

“…The redox state of TM elements depends on glass fabrication conditions (furnace temperature and atmosphere) and glass chemical composition . The atmosphere of ancient furnaces is assumed to be reducing because of combustion conditions . However, the absence of quantitative estimates of the oxygen partial pressure limits our knowledge on the know‐how of glassmakers concerning melting and fining conditions.…”

“…11 The atmosphere of ancient furnaces is assumed to be reducing because of combustion conditions. 12,13 However, the absence of quantitative estimates of the oxygen partial pressure limits our knowledge on the know-how of glassmakers concerning melting and fining conditions. So far, only a few studies have provided quantitative estimations of the oxygen partial pressure pO 2 in ancient furnaces: Bingham et al estimated pO 2~1 0 -1 -10 -6 bar for Roman blue-green glass 14 and Sellner et al estimated pO 2 10 -4 -10 -7 bar for late Middle Age glasses.…”

To be purple or not to be purple? How different production parameters influence colour and redox in manganese containing glass

“…Furthermore, apart from producing delicate vessels, Roman glassmakers were also able to control the production parameters to achieve certain colours. Iron, being a sand impurity, is always present in Roman glass in a rather reduced form, thus causing the glass to have a bluish colour with an absorption peak at 1100 nm (Ceglia et al, 2014). Through the addition of antimony or manganese oxides, iron in glass was oxidised to its yellowish form (main absorption peaks at 380, 420 and 435 nm) thus giving the impression of a colourless glass (Foster and Jackson, 2010;Jackson, 2005).…”