The board is of oak and was treated by conservators using acetone rosin, in the same way as the Coppergate bucket. The nails were of iron and needed to be treated to prevent corrosion.
The simplest method used for archaeological iron is to store it in a very dry environment, less than 15% relative humidity. In this case, however, very dry conditions would cause cracking and warping of the wooden board, so chemical methods of stabilisation were favoured.
Tannins
were used in the form of a weak tannic
acid solution applied to the exposed surfaces of the nails using a
small brush. This solution reacts with the metal to form a blue-black
iron tannate film. The film
acts as a corrosion-resistant layer, preventing damaging moisture and
oxygen from reaching the surface of the metal.
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