| 1. |
- Bring, Torun, et al.
(author)
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Potassium sulfate droplets and the origin of turbidity in alabaster glass
- 2006
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In: Glass Technology : European Journal of Glass Science and Technology A. ; 47:1, s. 15-18
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Journal article (peer-reviewed)abstract
- A study of the criteria required to manufacture multi-component semi-transparent silicate glasses, so called “alabaster” glass, has found that the optical effect is caused by non-crystal¬line potassium sulfate droplets. The droplets were characterized by use of XRD, SEM/EDX and Raman spectroscopy. The size range of the particles is in the order of 5-50 micrometers. It was found that the droplets consisted of potassium sulfate, even if other sulfate compounds were added to the glass. The amount of sulfate compound added, the melting temperature of the furnace and the melting time have significant effect on the optical density of the glass. The optical density of the glass can be correlated to the calculated surface tension of the host glass, suggesting that phase separation of a sulfate enriched liquid phase is part of the mecha¬nism forming the droplets. By adding pigments several different colours can be obtained, but the alabaster effect is not achieved during reducing conditions, thus it seems not possible to produce colours originating from reduced pigments. Pigments tested were Cr, Fe, Co, Cu, Au, Mo/Se, Nd and Ti/Ce/Se.
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| 2. |
- Stålhandske, Christina, et al.
(author)
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Gold ruby glasses : influence of iron and selenium on their colour
- 2006
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In: Glass Technology. - 0017-1050. ; 47:4, s. 112-120
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Journal article (peer-reviewed)abstract
- Colour development of gold ruby alkali silicate glasses, when various elements are added to the batch, has been investigated. Elements used in the study are selenium, iron, tin, lead, antimony, cerium, titanium and bismuth. The colours are presented and compared by their Lab coordinates. Among the elements selenium and iron are found to be important, and the role of these elements in colour development is discussed. Thermodynamic calculations show that important oxidation states are Fe2+ for iron and Se-0 and Se2- for selenium, and that higher melting temperature improves the colour, as it affects the oxidation states of both Fe and Se.
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