The University of Leicester Archaeological Services was called in to carry out this new
commercial project in the heart of Leicester, where new apartment blocks are going to be
built and our job was to record and rescue any of the archaeology that was going to be
damaged by the new development.
During the recording and the rescue of the archaeology on the site
we uncovered a Roman mosaic. It’s not like the Blackfriars mosaic in Leicester
which is one of the finest mosaics in Britain, which is the quality of flooring that only
the very rich could afford. This is the type of floor most houses in Leicester would have
during the Roman period.
There are a lot of challenges with lifting this mosaic,
it was winter, it was cold, it was minus degree weather and the mosaic itself
is not the highest quality. Over the 1500 years it’s been buried in the ground it’s
broken up so the individual tesserae are no longer bonded together. To lift it you need
to have a dry surface on to which you can successfully stick contact adhesive and you
need a bonded surface so that you don’t have to worry about individual tesserae falling
out, we have none of that with this project.
On the first day I arrived on site I hadn't actually seen the mosaic itself,
I’d only seen photographs and it’s very hard to judge
size by photographs and it was a lot bigger than I expected it to be.
I had a plan, we were going to dry the mosaic by pouring alcohol on the surface and putting
a match to it and the heat from the burning alcohol was supposed to dry the mosaic but
it was so cold, it was below freezing, that we were below the flash point of the alcohol
and we couldn’t actually dry the mosaic on that first day.
On the second day we decided that we needed to hold the mosaic together better so that
we had a better chance of lifting it, so it was a more cohesive object and to do that
we repointed all the tesserae with a traditional lime plaster. It held the tesserae together
and it gave us this nice smooth surface, which was much more practical for sticking to because
what we were going to do next was to stick hessian to the surface, to hold all the tesserae
together so we could then cut underneath and turn it over and lift it.
When we lifted it we had the hessian glued to the front of it and we had knives and something
called a slate rip, which is a long metal with a cutting edge on the front edge which
you can ram underneath it and cut underneath.
This freed it from the ground and we were
then able to slide thin pieces of metal and thin pieces of ply wood underneath the mosaic
by lifting it a little bit and sliding them in. That allowed us to put a big board underneath
so that then we could pull the section away from where we were working. We then wrapped
the whole thing up with cling film and we put another board on the top
and then flipped it over.
The mosaic was in a bit of a rough old state
when it arrived in the studio, so the first thing I had to do was take all the plaster
off the back and clean all the back up so that the tesserae were all exposed. Once I’d
done that it was necessary to consolidate the back because there was a lot of lose material
between the tesserae. So I consolidated all of that with a resin which I painted on
in solution and that soaked down between
and held everything together so it was all nice and consolidated.
Once that was dry I put a layer of sand and resin
over the back which completely smoothed and sealed the back of it so that when the
backing was put on it wouldn’t run down in between the tesserae. I then put a fibreglass
backing onto it, this was done with a chop strand mat and a liquid polyester resin which
is stippled in rather like you would if you were making a boat or something like that.
The slight problem with fibreglass is that it tends to distort a bit when it sets, there’s
a little bit of shrinkage. So to prevent shrinkage I put a steel frame into the back of it with
another layer of fibreglass over the top of it so it was embedded right into the frame
and very strong. Once that was all set the mosaic was turned over
and the hessian on the front was taken off.
In some ways it’s quite unusual to go to
this level of effort and cost to conserve a mosaic of this quality but actually because
of its poorer quality you can actually see the craftsmanship behind it. You can see the
sort of direction they were laying the stones in. You can see at one point that one of the
lines started to bend off so they’ve had to turn one line into three to create a straight
edge again. It’s these little human touches in it that
you can see that are important because they give you those glimpses into how it was made,
who made it, their attitude to work
that gives you that real insight into the people of Roman Leicester.