Plowden and Smith have a long history of dealing with the challenges of the preservation and conservation of ancient bronze artefacts. Archaeological bronzes can be very robust and survive hundreds of years in the ground. Once excavated, cleaning will reveal preserved details within a range of corrosion products. Many of these corrosion products are aesthetically pleasing and can retain important details about the burial site and manufacturing techniques. However, some bronzes can develop corrosion problems caused by chlorides  and this is commonly known as “bronze disease”. This corrosion continues to occur in normal room conditions, and if it is not treated it can be very destructive. Small localised areas of corrosion can be easily treated and then locally toned in to colour match the surrounding area, as bronze disease is often disfiguring.

Cleaning archaic bronzes requires a great deal of manual skill and knowledge of how metals corrode in order to determine dirt from corrosion products, which should be retained. Other metals such as gold and silver can also remain as inlays in the artefacts and cleaning techniques can be used to bring out these beautiful materials whilst carefully balancing the retention of the patina and corrosion products.

We offer a surveying and monitoring service for archaeological bronze collections to ensure that bronze disease does not develop. One such client is Compton Verney who has a significant collection of Chinese bronzes. One of the case studies illustrated above is of a ritual wine vessel and cover (guang), which dates from the Shang Dynasty, approximately 1100-1200 BC. It was in several pieces and required reconstruction in order to be able to appreciate the aesthetics of the piece.

For more information on Chinese Bronzes please visit Compon Verney’s website: http://www.comptonverney.org.uk/collections/chinese.aspx