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Archaeology/Wood Preservation


QUESTION: Hello, hope you had a very good thanksgiving. I have a question about the bricks and mortar that were encasing the chests in my discovered room. I have made them fire and salt glazed, I had a sudden idea about the mortar, would master stonemasons in the 1300's have used copper and or arsenic in mixing their mortars for preservation of the contents. Or would that have been a by-product mixing other items for the mortar.

ANSWER: Hi Lorie,  why do either?  Also arsenic was not known then.  But still why would they use it in the mortar?  What is your thinking?

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QUESTION: the test results were beginning to come in in my book and the items were being broke down and described by what was in them and when I got to the mortar I had a sudden inspiration about some of the ingredients,what you said about ways copper could be used for preservation and I went to the internet to see if copper could be used in mortar and if it had been used in the past,I found reference to copper-8 additive and mention of arsenic, then I looked up when arsenic began to be used and I found reference to it in history of Zosimos around 300 AD. So I thought if both of those items were known and used in ancient times, I wondered if it would be plausable to think that my characters who hid the treasure and were master stonemasons would have used those items for preservation techniques. Am I just being fanciful or would it be possible.

Hi Lorie,

Arsenic by a different name was known and it was used as a poison, like hemlock.  It was also used as a rodenticide.  Still is today but I've not seen it used in reference to mortar.  Arsenic can be absorbed through the skin and depending on how it was mixed could have killed the masons.  Not likely.  Copper could be used but making powdered copper to mix into the mortar would have been very time consuming and again would not serve that great a purpose.  So, yes, I think you may be making things more complex then needed.   The people in your book seemed eminently practical with skills that were remarkable but simple based on the technology they had at their disposal.  Best not to make it to complex.


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Ralph Salier


Archaeologist for the last 30 years. Norh American generalist and Hopwell culture/Red Ocher culture specifically. Lithics Expert and Ground Stone tools.


Past/Present clients
Numerous museums in US and Canada. Several University Anthropology Departments.

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