In the
practical part of our course, we all received a metal coin, waterlogged wooden
treenail and waterlogged leather to treat. This gives us valuable experience in
how to treat these kinds of objects and encourages us to link theory with
practical treatments.
Metal Coin
So we
received our very first objects; a silver 1696 Sixpence for Sam and a Shilling
for Tanya.
Both were tarnished and had adhesive and fibres stuck to one side.
At
first, we spent the majority of the time just staring at them, wondering what
on earth we were supposed to do and how everyone else seemed to know what they
were doing. Eventually with some help from the tutors, we pulled ourselves
together and started thinking logically.
The
conservation requirement was to clean for display – remove the adhesive and
fibres, and remove some of the tarnishing if necessary.
We had
to figure out exactly what the problems were (adhesive, fibres, tarnishing) and
how to solve them. There are a lot of solvents in the lab that can remove
adhesives but we used acetone because research told us that it seemed to
be the least harsh and most effective for the job.
Did you know? Nail
varnish remover is made from Acetone and can be used to remove stubborn
adhesives and tape!
Acetone
and a cotton swab removed the fibres along with the adhesive - this was
surprisingly effective and the removal was much quicker than either of us had
expected. Two problems solved!
We also
used a cotton swab with calcium carbonate in water to remove some (but not
all!) of the tarnish to keep some of its evidence of use. This turned out to be
more difficult – it is hard to get an even ‘old’ look without making super
shiny spots. It was almost like using sandpaper to remove a very thin coating
of tarnish.
And so
here it is – one of our very first conserved objects!
Before
After
Waterlogged Wooden Treenail
We then
received waterlogged
wooden treenails, recovered from Newport Ship. The conservation requirement
here was different; these treenails are going to be handled by visitors to the
museum. This meant that after treatment, it should still look and feel like
wood (but dry!)
Waterlogged: When most
of the spaces in an object have been filled with water, which is now supporting
it. Waterlogged objects can come from underwater or burial.
Wet wood!
The
first step in successfully drying waterlogged objects is to keep them wet!
Removal of the water without replacing it will result in collapse. To prevent
this collapse, we bulked (filled the spaces that needed support) our treenails
with Polyethylene
Glycol (PEG) before freeze-drying.
Fun fact: If you check
your shampoos and/or body wash, you might find that there is PEG in there too!
Freeze-drying
involved freezing the treenail before placing into a vacuum; the ice inside the
wood then changed straight into vapour, missing out the liquid phase and
leaving the PEG in its place as structural support.
When
they came out of the freeze-drier, the treenails were nice and dry!
Nice and dry!
Waterlogged Leather
Another
waterlogged object we received were pieces of leather excavated from Bute Park
outside Cardiff Castle. What look like scraps of leather are actually really
awesome because it is a part of history from right outside of our lab!
Wet
You
would think an acidic environment is bad, but leather is slightly acidic. This
is why we checked the acidity of the water when we were storing them.
We then placed the leather in ethylenediaminetetraacetic
acid—say that five times fast! It’s more commonly known as EDTA, a chelating
agent that draws out potentially damaging metals from the leather.
We had
to work out the percentage of glycerol in water we needed and used it in the
leather in the same way that we used PEG for the waterlogged wood. We then
shaped the leather into how we wanted it before freeze-drying.
Dry!
These were some of our group projects that we worked on alongside solo objects. So many objects, so little time! Stay tuned for more!
