Wednesday, 11 December 2013

Cannon you believe it? The time and money it takes to conserve artefacts salvaged from shipwrecks

You may have seen in the news last week that further diving at the Elizabethan wreck that sank off Alderney in the Channel Islands, UK in the 16th Century has been carried out by the Alderney Maritime Trust and staff from Bournemouth University. They have uncovered three cannon and "substantial ship timbers" in addition to over 1,000 artefacts that were salvaged from the first dive to the wreck in 2008. The unnamed ship sunk in November 1592 and was discovered by local fishermen Bertie Costeril and Fred Shaw in 1977.

Mike Harrison, coordinator trustee, said more work on the site was going to go ahead next summer and explained the large lapse in time between dives by stating that "[t]hings move very slowly with marine archaeology, the work we've done in the last few years... has been conserving objects." However he also noted that "it's very, very expensive... we've got a lot of fundraising to do, it's tens of thousands of pounds, conserving a cannon is £10,000 for example."

I took a look in our online archive to read more about conservation in maritime archaeology and came across the article 'In situ conservation of cannon and anchors on shipwreck sites' by Ian Donald MacLeod in a 1996 issue of Studies in Conservation. In the article the author explains how a wrought iron anchor and a cast iron carronade from the wreck of HMS Sirius (1790) received In situ electrolysis treatment using sacrificial anodes in the shallow waters off Norfolk Island in the South Pacific Ocean.This pre-treatment stabilises the artifacts and ensures that they can be safely recovered and transported.

Monitoring on the seabed and in the laboratory showed that approximately 80% of the chlorides had been removed from the carronade before excavation. The cathodic
pre-treatment results in a significant improvement in the quality of the surface of the metals. He argues it is possible to maintain artifacts on the seabed by continued use of sacrificial anodes.

>> Read the full article for free

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