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.

中文翻译：

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50种色泽：厚度，铁氧化还原和锰/锑含量如何影响罗马玻璃的感知色和固有色

本文通过光学吸收光谱法研究罗马玻璃，以提供一种客观的方法来定量评估颜色。该数据集由来自西欧各个站点的165个钠钙硅酸盐玻璃样品组成，主要是从公元一世纪到四世纪，并且包含可变数量的铁，锰和/或锑。确定铁的氧化还原比和颜色坐标（基于CIELab颜色系统），并将其与样品的厚度及其锰/锑含量相关联。结果表明，厚度是讨论玻璃色调时的关键参数，从而导致玻璃物体的“内在”和“感知”颜色之间的区别（即，厚度归一化为1 mm的物体的颜色以及其原始色的颜色）厚度）。一个* -一个比色参数确定玻璃那么绿。还考虑到锑/锰含量与铁氧化还原和玻璃颜色之间的重要关系，从而导致定量论证，使锑脱色玻璃成为氧化度最高和无色的玻璃。