Sixteen Years of Mechanical Cleaning

Conserving and Sharing the Bredon Hill Roman Coin Hoard: Part 2

The cleaning of the coins is a huge task. We opted to try and acquire the skills in house through specialist training by a conservator. We have a wonderful team of volunteers who have been together for years, initially with Alan Jacobs at Worcestershire Archive and Archaeology Service and since 2007 with the Museum Service. They have worked on a myriad of different projects and have a wealth of experience in collections care. Many of the  projects have been far from glamorous.

As a team, they had initially begun cleaning, marking and upgrading the packaging of Worcester City Museum‘s collection of human remains following the publicIMG_1506ation of DCMS Guidelines on the Care of Human Remains in Museums. They also reboxed small finds from Worcester’s large excavations in the 1970s, 80s and early 1990s at Deansway, Sidbury and Blackfriars. Finds are mounted in plastozoate which are set into crystal boxes with a handy little length of linen tape underneath the plastozoate so we can easily pull the objects out of their box with minimal disturbance. The silica, Stewart boxes and humidity strips have all been replaced.

In 2012 the largest assemblage of medieval roof tiles ever found in Worcester were discovered unexpectedly during roofing work on the garden wing at The Commandery. Our volunteers cleaned, weighed, measured, photographed and catalogued the whole assemblage and passed the data back to archaeologists for publication. The find was significant because Worcester is unique in having a system of tile stamping in this period. In effect it represents an early form of building control. The thatched roofs of the City were a major fire hazard and in 1467 the city ordinances introduced compulsory tiling, stating that

‘for the prevention of fire neither wooden chimneys nor thatched roofs shall be allowed thenceforward; by midsummer’s day next coming, the wooden chimneys should be replaced by brick or stone, and the thatched roofs by tiles’

Our volunteers recorded around 20 maker’s stamp patterns on 150 tiles. Around 20 further tiles were collected and recorded that were marked with tallies or showed animal prints

In 2012 we worked on a collection of plaster statues from the personal collection of Walter Gilbert, the founder of the Bromsgrove Guild. The statues had been on loan to Worcestershire County Museum for many years but had recently been donated by Walter Gilbert’s family. The statues were scheduled to be used in an exhibition at Worcester Art Gallery and Museum called Edwardian Elegance. Our volunteers worked over the weeks of summer 2012 using soft brushes and museum vacs to clean them for display.

Volunteers being trained by Lizzie in mechanical cleaning techniques
Volunteers being trained by Lizzie in mechanical cleaning techniques

Another collection of Bromsgrove Guild material chosen for display in our Edwardian Elegance exhibition came from the Regent Palace Hotel off Piccadilly in London. Painted windows crafted by the Bromsgrove Guild were returned to Worcestershire after removal from the building. They were covered on one side with a century of grime and our volunteers spent weeks cleaning them carefully with cotton buds. The glass is on display at Worcestershire County Museum.

So, In Autumn 2014 our volunteers began their training, funded by the Art Fund Treasure Plus Scheme, in cleaning copper alloy Roman Coins with Lizzie from the Staffordshire Hoard Project at Birmingham Museum Trust. She taught our volunteers, over three days, how to remove 1700 years of Cotswold mud.

The coins are late 3rd century radiates and have very little silver content, thus the results were never going to be spectacular.  This was something we only realised with time. It was a huge learning curve for everyone and involved learning to work comfortably using microscopes and scalpels. The mud was ‘caked’ in a solid film on the coins and involved careful use of the scalpel to remove the film whilst not damaging the surface of the coin and exposing the copper material underneath.

To loosen/moisten the mud, acetone was applied using cotton buds prior to the use of the scalpel. Initially each volunteer completed one coin a day and although they improved on the tally in time, it was still a very slow process. One of our volunteers calculated that if we didn’t speed up it would take us 16 years to complete our work.

Our breakthrough came in April 2015 when we attended a Symposium in Bath and heard about the conservation work which had been taking place on the Beau Street Hoard.

Supported by the Art Fund and The Headley Trust


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