Radiocarbon age of consolidants and adhesives used in archaeological conservation
Radiocarbon age of consolidants and adhesives used in archaeological conservation
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DOI：
10.1016/j.jasrep.2019.03.023
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发表时间：
2019-04-01
影响因子：
1.6
通讯作者：
Grant, Tara
中科院分区：
文献类型：
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作者：
Crann, Carley A.;Grant, Tara
用于保存考古文物的粘结剂和粘合剂必须在对文物进行放射性碳测年之前小心移除，否则放射性碳签名将受到损害。因此，最重要的是了解人工制品是如何保存的，以及使用了哪些保存产品，以便确定：(1)人工制品上取样的最佳位置；(2)如何物理和/或化学地移除固化剂；以及随后(3)是否成功移除了固化剂。前两个考虑因素是考古学家、保护人员和放射性碳实验室之间的沟通问题，但第三个考虑因素可能有点难以确定。考古学家通常知道艺术品的大致时间段，因为它是在被发现的背景下发现的，所以当年代不像预期的时候，固化剂可能没有完全被移走。然而，这可能是纯粹的猜测，除非知道固化剂(老者或年轻人)的放射性碳特征。本文介绍了考古文物保护中常用的21种固结剂和粘结剂的放射性碳和稳定同位素分析结果。固化剂和粘合剂涵盖天然材料(动物胶和鱼胶、树脂胶、淀粉)和合成材料(丙烯酸、聚醋酸乙烯酯、聚乙烯丁醛、聚乙二醇、甘油、纤维素醚、纤维素酯、氰基丙烯酸酯和可溶性尼龙)，它们是从现在常用的材料中挑选出来的，以及一些历史上使用过但由于老化质量较差而现已避免使用的材料。这篇论文将提供一些数据，这些数据可能表明年轻的或陈旧的保存方法可能会扭曲放射性碳年代，了解较老样品的保存历史的重要性以及如何解释这些结果。还提供了固结剂和胶水的稳定同位素特征，因为分析成本低廉，是对放射性碳分析的补充，可以用来证实从考古样品的偏置放射性碳年代收集到的污染怀疑。最后，我们给出了推动该项目的案例研究-真空浸渍PVA胶的碳化残留物的分析。
Consolidants and adhesives used to conserve archaeological artifacts must be carefully removed prior to radiocarbon dating of the artifact, otherwise the radiocarbon signature will be compromised. It is therefore paramount to understand how the artifact was conserved and which conservation products were used in order to determine: (1) the best location on the artifact to sample; (2) how to remove the consolidant physically and/or chemically; and subsequently (3) whether or not the consolidant was successfully removed. The first two considerations are a matter of communication between the archaeologist, the conservator, and the radiocarbon laboratory, but the third consideration can be a bit tricky to determine. The archaeologist usually knows the approximate time period of the artifact given the context in which it was found so when the age is not as expected, it is possible the consolidant was not completely removed. However, it can be purely speculation unless the radiocarbon signature of the consolidant (old or young) is known. Here we present results from the radiocarbon and stable isotope analyses of 21 consolidants and adhesives commonly used for archaeological conservation. The consolidants and adhesives cover both natural (animal and fish glues, tree resins, starches) and synthetic materials (acrylics, poly(vinyl acetate), poly(vinyl butyral), polyethylene glycol, glycerol, cellulose ethers, cellulose esters, cyanoacrylates and soluble nylon) and are selected from those commonly in use now, as well as a few that were used historically but are now avoided due to poor aging qualifies. This paper will present data that may indicate in which direction - young or old - conservation treatments may skew radiocarbon dates, the importance of knowing the conservation history of older samples and how these results should be interpreted. Stable isotope signatures of the consolidants and glues are also provided as the analysis is inexpensive and complimentary to the radiocarbon analysis and could be used to corroborate suspicions of contamination gleaned from offset radiocarbon ages of archaeological samples. Finally, we present the case study that motivated this project the analysis of carbonized residuals vacuum impregnated with PVA glue.