British Museum blog

After-excavation care at Amara West

Elisabeth Pamberg, archaeological illustrator/conservator

Salt crystals on the rim of beer jar C8008

I visited the stores where we keep the objects excavated from the site, to check they were in good condition. Objects from a site like this one often contain salts that could damage them, so I wasn’t surprised to observe that several objects had salt crystals on them, particularly the pottery and some stone sculpture.

The artefacts retrieved at Amara West are subject to environmental conditions which include high humidity and salinity, the result of the site’s proximity to the Nile. Ceramic and stone buried in soil absorb the salts present in the deposits.

Beer jar C8007 after desalination this week

Following my advice, and discussions with Marie Millet and Neal Spencer, two beer jars from grave 201 were chosen for treatment, as they were affected by salt, with a thick visible layer of white concretions.

The salts are harmful and are not only an aesthetic issue; they obscure the object’s surface and can lead to surface exfoliation – the surface lifting off. Eventually, the crystallisation of salts can lead to disintegration.

The most efficient way to extract salt consists of soaking the objects in water over a long period of time, though extra steps need to be taken with fragile objects, or those bearing paint.

The removal of soluble salts can be a very lengthy procedure. In this case, the jars were bathed repeatedly in plenty of warm water for a period of eight days with the water being changed every day.

Unfortunately, no distilled or deionised water and conductivity meter (to measure the decreasing level of salt) is available here. Nonetheless, soluble salts appear to have completely disappeared from the jars, ensuring their long-term preservation.

Looking to future seasons, we might consider testing salt levels in the local river water, which is used for washing all pottery prior to study, recording and storage.

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