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Anglo-Saxon Brooch
Weighing just over 5g this copper alloy annular brooch was discovered buried in an Anglo-Saxon grave. The brooch was used as a fastening device for clothing.
There is evidence of extended use as the brooch is very thin where cloth would have been pulled through. The pin of this brooch is missing; however, it would have been attached around the narrow part of the band with the opposite side acting as a pin constrictor.
The surface of the object was bright green and orange which indicates active bronze disease, there were accretions of dirt caked on the surface with layers flaking off – the object could have been lost without treatment.
Treatment:
Dry cleaning was undertaken to remove chloride pollutants and loosely adhered dirt. A soft bristled brush was used in a circular motion to remove soiling. Under magnification cocktail sticks and a scalpel with a 15 blade were used to pick at accretions and corrosion, this was done at a shallow angle to prevent pressure damage.
The object was then wet cleaned using IDA on a cotton swab under extraction. Small circular motions and rotations of the swab were used to remove the majority of the accretions. This was an extremely effective and non-damaging cleaning method.
The brooch was then fully submerged in a beaker of 3% Benzotriazole (BTA) in Industrial Denatured Alcohol (IDA) and placed in a vacuum chamber for seven hours. The object was removed from the beaker using plastic tweezers and left to fully dry. Finally, three thin coats of 5% Incralac in Toluene were applied using a soft bristled brush, each coat was left to fully dry before application of the next coat. Due to the slower evaporation time brush strokes have time to even out and create a smooth coat over the object.
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