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Experimental mixing of natron and plant ash style glass: implications for ancient glass recycling

Experimental mixing of natron and plant ash style glass: implications for ancient glass recycling

Scott, R. B. ORCID: 0000-0001-9963-3972, Neyt, B., Brems, D., Eekelers, K., Shortland, A. J. and Degryse, P. (2017) Experimental mixing of natron and plant ash style glass: implications for ancient glass recycling. Glass Technology – European Journal of Glass Science and Technology Part A, 58 (1). pp. 8-16. ISSN 1753-3546 (doi:

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The practice of re-melting glass was well known, certainly from the Roman period onwards. This can be seen not only in ancient literary evidence but also in the archaeological evidence, collections of broken glass have been found in, for example, Pompeii (79 AD) and the Iulia Felix shipwreck (Third century AD). Elevated levels of certain transition metals in archaeological glasses are interpreted as indications of the mixing and/or recycling of different glasses. Assumptions have been made that all glasses could be recycled, but to what extent are these valid? Why does the evidence for the recycling of glass only occur from the Roman period onwards? From the middle of the First millennium BC to the Ninth century AD, natron glass was the predominant glass type in the Mediterranean and Europe, however, plant ash glass was still in use in some areas. To test the effects on the final product of mixing different composition glass types, experimental glasses were made by mixing varying quantities of replica plant ash glass, replica natron glass, and a modern glass. At low temperatures crystalline material formed in the products containing replica plant ash glass. As the plant ash glass content increased, so too did the amount of crystalline material produced. This is due to a combination of the glass compositions and the firing temperature. It appears that natron type glass can be more easily recycled at lower temperatures, although, if a high enough temperature is used then most glass types can be recycled. Early furnace technology, i.e. the vertical heating chamber furnace, may not have been able to achieve these high temperatures, hence the widespread practice of recycling did not begin until after the invention of glassblowing which required a change in the furnace technology to the use of a horizontal heating chamber furnace.

Item Type: Article
Uncontrolled Keywords: archaeological glass, glass recycling, experimental archaeology
Subjects: T Technology > T Technology (General)
Faculty / Department / Research Group: Faculty of Engineering & Science
Faculty of Engineering & Science > School of Science (SCI)
Last Modified: 27 Jul 2020 15:28
Selected for GREAT 2016: None
Selected for GREAT 2017: None
Selected for GREAT 2018: None
Selected for GREAT 2019: None
Selected for REF2021: None

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