Tabatha Barton, Archaeology Curator and Collections Conservator
Funded by the South-East Museums Development Programme and the Association for the Study and Preservation of Roman Mosaics
Bancroft Villa Mosaic:
Conservation Project
Bancroft Villa is one of more than 8 Roman villas in Milton Keynes, it was built as a farmstead in the 1st century CE, and underwent a number of renovations including adding bathhouse complexes and mosaics until it fell out of use in the 5th century CE.
History
A model of Bancroft Villa showing the main house and the bathhouse wing (to the left), as well as the small octagonal building on the side.
A photo of the villa during excavation. You can tell that this is part of the bathhouse because in the right hand corner there are stacked tiles. Those tiles would have been under a pavement and would allow for hot air to pass underneath and heat the floor. In the background, you can see the mosaics!
A floor pavement made of tesserae which are laid in plaster. Tesserae are small squares of stone and ceramic (sometimes even glass) which make up the patterns you see on the mosaic.
The mosaic was made by the Cirencester workshop.
The most unique part of the mosaic is this laurel wreath- there are only two other examples of it in Roman Britain!
Room 8 Mosaic
© Milton Keynes Development Corporation. Crown copyright. Used under the Open Government Licence v 3.0 http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/ Image courtesy of Milton Keynes City Discovery Centre.
A close-up of the laurel wreath motif from the Room 8 mosaic. The small squares used to make this design are called 'tesserae', and the design is considered to be 'fine' because of how small the tesserae are.
A photo of the Room 8 mosaic during excavation. See how the rest of the site has been excavated around the mosaic? This is so that the archaeologists can 'lift' the mosaic in sections without disturbing the tesserae.
What was Room 8 Used for?
Room 8 is the largest room in the bathhouse complex at Bancroft Roman Villa.
But what could this room have been used for?
The large size of the room and its position in the bath complex indicates that it was likely a reception room!
An illustration made of the mosaic after conservation.
Only two panels (2 metres) and 6 metres of coarse border were found during excavation. The mosaic likely would have taken up most of the 8.5 by 6 metre room!
The mosaic was covered with netting and PVA adhesive (like white glue!) so that it could be cut into pieces and lifted by the archaeologists.
The pieces were then stored upside down until 2019!
Excavation and Lifting
Various photos from the excavations in the 1970's and 80's
The mosaic being covered in PVA and netting.
This is a photo showing the project half finished! Here we can see pieces of the mosaic already covered in netting and PVA and having been flipped over onto boards in the foreground. While in the background, we can see the rest of the mosaic still waiting for it's turn!
How do you put an upside down mosaic together?
First, you make sure all the pieces fit together.
The mosaic is very heavy, so each piece was put on a piece of wood and slid into place like a giant jig-saw puzzle.
Putting the Puzzle Together
These are the trays that the mosaic was stored in since excavation. Luckily, all of the pieces were still on their original boards since being removed from the site, so we did not have to pick up any of the mosaic in order to take the pieces out and move them around.
Once we put together the mosaic, we needed to clean it.
How do you think you clean a mosaic?
We used vacuum cleaners with the nozzles covered to remove the dirt (and not the tesserae!)
Cleaning the Mosaic
How to clean a mosaic?
•Step 1: Dry cleaning (to remove dust and loose dirt)
•Museum vacuum and a tough brush
•Step 2: Wet cleaning (to remove most dirt and stains)
•Water
•50:50 water and acetone
•Brush, -not- cotton swabs
•Step 3: Mechanical cleaning (to remove encrustations)
•Rotary tool
Luckily, we only had to use step one of this!
Before we could turn the mosaic over, we needed to re-back it with something to make it sturdy.
We decided to use hessian as a release layer, and then re-back the mosaic with plaster.
Re-backing the Mosaic
What are those numbers?
Since we could not see the design of the mosaic once it was covered in plaster, we needed to put arrows (pointing for which way was up) and numbers on the back so we knew which piece was which!
The proposal for backing the mosaic was as follows:
•Step 1: Apply hessian scrim to the back of the mosaic with EVA
•Acts as a separating layer
•Step 2: Apply a thin layer of plaster to the back of the mosaic
•This allows us to pick the mosaic up in pieces without it breaking
•Step 3: Apply a second thin layer of plaster and incorporate wire mesh
In the end, we did not need to go to step 3 because step 2 worked so well!
We turned the mosaic over onto an aluminium honeycomb backing. Each piece was flipped over in a padded foam and wood box, and then slid onto the board which had been prepped with epoxy resin adhesive.
We were able to get the jigsaw to fit together because we used a tracing of the mosaic to outline exactly where each piece went.
Turning Over the Mosaic
Did you know?
Aluminium honeycomb boards are commonly used in mosaic conservation. They are lightweight, but very strong. They are also used in making space ships!
How to turn over a mosaic:
•Step 1: Cut the 1:1 plan of the mosaic into pieces and lay it out on the epoxy board
•Step 2: Cover the back of the mosaic piece and the corresponding front part of the board in epoxy
•Step 3: Gently place the mosaic section onto the board
•Step 4: The entire mosaic should be adhered in quick succession to allow for movement before the adhesive sets
And success!
How did we do?
The netting and PVA which had been holding the mosaic together for decades turned out to be a lot harder to remove than we thought.
In the end, we had to use wall paper steamers to soften the netting, allowing us to take it off by hand!
Removing the Netting
How to remove the netting:
•Option 1: Use water to remove the netting
•The netting is adhered onto the mosaic with PVA, this is soluble in water
•Option 2: Use hot water to remove the netting
•The heat will speed the process up
•Option 3: Use 50:50 acetone and water to remove the netting
•If the PVA has cross-scissioned, stronger solvents may be necessary
•Option 4: Steam the netting off
In this instance, we did have to go to our last option!
If you've ever removed a carpet from a floor, you know the floor underneath always need a clean. The same is true of a 2000 year old mosaic floor!
Once we'd removed the netting, we had to clean the front of the mosaic using -you guessed it- the vacuum cleaners.
Cleaning the Front
Ethics: How far do you go?
Since finishing the conservation, I often get asked if I am going to varnish the front of the mosaic, or try to bring out the colours a bit more. The answer is always the same. No.
When you work in a museum, you are governed by a set of ethical codes. People don't come to museums to see things that are shiny and new, they come to museums (at least I do) to see old things and learn about them. So when we undertake conservation projects, our goal is to make an object stable so that we can share it with the public, and not to make it look new!
How to clean the front of a mosaic:
•Step 1: Dry clean the front of the mosaic
•Step 2: Wet clean the front of the mosaic
•Step 3: Mechanically clean the front of the mosaic
We did not need step 3 luckily!
The last thing we had to do was fill in all of those gaps. Why did we do this? Gaps can cause further damage to the mosaic, as well as encourage mould growth!
Our goal was not to restore the mosaic (to make it look new), but to conserve the mosaic (to stablise it for display).
Conservation vs Restoration
How to gap-fill a mosaic:
•Step 1: Assess whether consolidation is necessary
•Step 2: Consolidate friable tesserae
•Use 10-20% Paraloid B72 in acetone
•Step 3: Consolidate the gaps in the mosaic
•Option 1: Use previously removed coloured tesserae to complete the pattern
•Option 2: In-fill the gaps with plaster
•Step 4: Consolidate the edges of the mosaic
•Use the rest of the plaster to protect the edges and smooth out the rest of the board
How do we gap-fill a mosaic?
We used plaster mixed with pigments to make fake tesserae which we then stuck into place! This restoration follows the 'six foot six inch rule' which means that, a conservation gap-fill should be invisible at six feet, but very obviously a gap-fill at six-inches!
The mosaic will be part of our Roman section in the upcoming Ancient Galleries at the Milton Keynes Museum.
It will be integral to telling the story of the Roman occupation and the daily life of the Romano-British people who lived in Milton Keynes.
What's Next?
Thank you to all the wonderful volunteers who worked on this mosaic with me! It would not have been possible without you!
Thank you for reading!
For more information: https://miltonkeynesmuseum.org.uk/
