TY - JOUR
T1 - 50 shades of colour
T2 - how thickness, iron redox and manganese/antimony contents influence perceived and intrinsic colour in Roman glass
AU - Bidegaray, Anne Isabelle
AU - Nys, Karin
AU - Silvestri, Alberta
AU - Cosyns, Peter
AU - Meulebroeck, Wendy
AU - Terryn, Herman
AU - Godet, Stéphane
AU - Ceglia, Andrea
PY - 2020/5/13
Y1 - 2020/5/13
N2 - Roman glass is studied here by means of optical absorption spectroscopy, in order to provide an objective method to quantitatively evaluate colour. The dataset is composed of 165 soda-lime silicate glass samples from various western European sites, mainly dated from the first to fourth century AD, and containing variable amounts of iron, manganese and/or antimony. Iron redox ratios and colour coordinates (based on the CIELab colour system) are determined and put in relation with the thickness of samples and their manganese/antimony contents. Results reveal thickness as a crucial parameter when discussing glass hues, thus leading to a differentiation between the ‘intrinsic’ and ‘perceived’ colour of glass objects (i.e. the colour of the object with the thickness normalised to 1 mm, and that with its original thickness, respectively). Apart from HIMT and purple glass, the concentration of ferrous iron appears to be correlated with a* — a colourimetric parameter determining how green the glass is. Significant relations of antimony/manganese contents versus iron redox and glass colour are also considered, resulting in quantitative arguments to entitle antimony-decoloured glass as the most oxidised and colourless glass.
AB - Roman glass is studied here by means of optical absorption spectroscopy, in order to provide an objective method to quantitatively evaluate colour. The dataset is composed of 165 soda-lime silicate glass samples from various western European sites, mainly dated from the first to fourth century AD, and containing variable amounts of iron, manganese and/or antimony. Iron redox ratios and colour coordinates (based on the CIELab colour system) are determined and put in relation with the thickness of samples and their manganese/antimony contents. Results reveal thickness as a crucial parameter when discussing glass hues, thus leading to a differentiation between the ‘intrinsic’ and ‘perceived’ colour of glass objects (i.e. the colour of the object with the thickness normalised to 1 mm, and that with its original thickness, respectively). Apart from HIMT and purple glass, the concentration of ferrous iron appears to be correlated with a* — a colourimetric parameter determining how green the glass is. Significant relations of antimony/manganese contents versus iron redox and glass colour are also considered, resulting in quantitative arguments to entitle antimony-decoloured glass as the most oxidised and colourless glass.
KW - Antimony
KW - Colour
KW - Iron redox
KW - Manganese
KW - Optical absorption spectroscopy
KW - Roman glass
UR - http://www.scopus.com/inward/record.url?scp=85084634536&partnerID=8YFLogxK
U2 - 10.1007/s12520-020-01050-0
DO - 10.1007/s12520-020-01050-0
M3 - Article
AN - SCOPUS:85084634536
VL - 12
JO - Archaeological and Anthropological Sciences
JF - Archaeological and Anthropological Sciences
SN - 1866-9557
IS - 6
M1 - 109
ER -