Monday, June 20, 2011

2011 Condition Survey: Salts

We start the season at Gordion with a condition survey of the museum collection. A survey is an overview of the collection, where we quickly examine each object on display and note condition issues. The survey is completed on a yearly basis, allowing for comparison of survey results with previous years so that objects in need of attention can be prioritized.

One of the condition issues we have encountered is the presence of salts, a common problem with some archaeological materials, particularly ceramics. When hearing a conservator talk about salts, the white crystalline material found in the common kitchen, possibly occupying a shaker marked with an "S" on your dining room table, might come to mind. Actually, this is not too far off the mark, because table salt, aka sodium chloride, is simply a purified form of one type of salt.

It may sound odd that salts are present in archaeological objects, but it is a fairly common occurrence, since salts are present in burial dirt. If they are not removed, then salts may either obscure the surface or cause damage to an object.

During our survey, we discovered salts present on this ceramic:

The salts are the powdery white crystals seen here on the rim.
The salts have caused some damage to the surface.

A particularly interesting, and unusual, discovery is the blue area in the above green box, which is located in a fill rather than the original ceramic. Examination of this strange blue area revealed hair-like salt crystals that are not found on the other, non-blue fill material, and is different in shape from the other salt crystals present on the ceramic.

The blue area of the fill contains hair-like crystals that are
different from other salt crystals found on the ceramic.

The objects conservation team plans on treating this ceramic to remove the salts, via a process called desalination. Samples of this strange blue material may be removed for analysis back in the US, at one of the conservator's home laboratories. The analysis may shed light on why and how these crystals were formed on the fill material. Stay tuned for an update on this treatment!

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