The Museum of London in partnership with the Jewellery Industry Innovation Centre (JIIC) and the Birmingham Institute of Art and Design (BIAD), which is part of Birmingham City University (BCU), is using state-of-the-art technology to investigate the Cheapside Hoard, the greatest hoard of Elizabethan and Jacobean jewellery in the world, to find out what methods could have been used to create these pieces. Selected items from the Cheapside Hoard are currently on display at the Museum of London.
Dr Ann-Marie Carey, a research fellow at JIIC/ BIAD, comments, "When we received photographs of the Cheapside Hoard, we were fascinated with the level of detail in the jewellery. We started to ask ourselves how such pieces were made and to understand the story behind them. Until now, there had been little research into the craftsmanship involved."
Working with Hazel Forsyth; Senior Curator of the Medieval and Post-Medieval Collections at the Museum of London; Ann-Marie and Keith Adcock, Senior CAD CAM Technologist at JIIC/BIAD spent several days at the museum taking photographs and digital scans of the items for analysis.
Unfortunately, some of the collection had suffered significant deterioration over the years. This meant that, before the team could determine how some of these pieces were created, they needed to visualise how they would have previously looked by either partially or completely recreating them. This digital recreation takes the project beyond normal curatorial practice. To do this the JIIC team used a range of techniques from utilising photographs to help recreate objects in CAD, to laser scanning the pieces, or a combination of both!
One of the Cheapside Hoard pieces to suffer considerable corrosion was the gild brass verge watch signed by G.Ferlite. Unlike other items in the collection, this could not be laser scanned easily. Keith explains, "Laser scanners do not work well with shiny objects such as gem stones, glassware and polished gold. For us to accurately scan the Ferlite watch we would have had to chip out the enamel and spray it white, which obviously we weren't going to do. Nonetheless we scanned the dial of the watch but it needed CAD interpretation and enhancement."
The watch face was recreated with artistic Computer-Aided Design and Computer-Aided Manufacturing (CADCAM) software, ArtCAM JewelSmith. With Delcam's software, Keith imported a photograph of the watch face and using ArtCAM's 'Relief from Image' tool created a model surface. This removed the need to trace around every part of the imported image to create the vector artwork. Keith comments:
ArtCAM is absolutely fabulous for interpreting photographs and creating textures."
However, due to the effects of the corrosion on areas such as the day-dial on the right hand side of the watch face, Keith needed to alter some of the automatically generated reliefs. Fading out the photo, Keith used ArtCAM's advanced vector drawing tools to quickly trace around the parts he wanted. He then remodelled areas using ArtCAM's 'Shape Editor' and combined these with the reliefs generated from the scan data. Smoothing tools were then used to soften the surface finish before ArtCAM rendered the piece as it would have looked prior to receiving its enamel finish.
The next step was to 3D print the model. Keith quickly modelled the 3D shapes in ArtCAM, which would act as the supports for the resin model. Using ArtCAM's advanced STL Creation, he then created the necessary files which were sent to the printing machine (Envisiontec Perfactory). Keith concludes, "ArtCAM was a vital tool in our project!"