15th April 2016 - Coin Hoard Blog - Jersey Heritage

Throughout the time we've been taking the hoard apart we've constantly been asked if we can see the bags the coins were in and we've always had to say no, they just seem to have been poured into a hole in the ground. Now though for the first time we have found one and it looks like a leather purse full of coins.

We found it near one edge of the hoard, right on the bottom, which suggest it was dropped iin the hole along with the first items.  The purse, if that's what it is, is about 80mm by 40mm and perhaps 40mm deep.  The leather is quite thick, about 2.5-3mm and is "ribbed" with horizontal lines about 3mm apart.  We can't tell yet whether these are incisions part way into a sheet of leather or whether it's assembled from a long strips of bootlace thin leather.  Next to the purse are two thick 40mm copper alloy rings, at least one of which appears to be bound to the purse so they seem to be fittings, perhaps for a belt?  The purse is full of coins which look like the Armorican staters we're finding in the rest of the hoard but as they are still corroded and covered in earth we can't tell what tribe or type they are yet.

The leather is incredibly fragile so it's been a difficult job to excavate the surrounding coins without damaging it but we have now reached its base most of the way around the purse.  The way we've decided to excavate and remove it is to take out all the surrounding coins in a 5cm ring around the purse down to the earth base of the hoard.  When it stands isolated in this way we can then cut down through the earth base it sits on and carry it out of the hoard on this as a support.  The leather is so weak that we aren't going to attempt to take the coins out of the purse  at this pointas it would probably crumble as we did it.

Once we have the purse away froom the hoard we will get a good chance to study and record it.  The conservation treatment itself may prove tricky.  The usual thing to do would be to treat the leather with PEG freeze drying.  This technique is designed to remove the water from the leather without causing damage.  If it were allowed to just dry out in the air, the leather would twist and shrink till it just cracked into brittle fragments.  This is because of capillarity, which is the "sucking" power of water between sheets of material.  I'm sure you've seen how water can stick two sheets of plastic together so that you literally can't pull them apart.  Well, when something like archaeological leather or plant fibres dry out the same suction happens inside each cell and fibre.  This sucks the cell walls together as the water is lost and can destroy them.  What we do instead is slowly introduce a water soluble wax (polyethylene glycol or PEG) into the still wet leather where it penetrates and strengthens it.  When this is done the leather is placed in a freeze drying vacuum chamber.  The water in the leather freezes and then the vacuum slowly takes it away as water vapour.  This means that over time the object loses its moisture without actually ever being wet during the process and thus there is no capillarity damage.  The problem though is that we may still have the coins in there when we come to start the treatment and although the process might not actually harm them it would stop us cleaning them to find out what coins they are.  This is obviously really important to us as they may have been something special to the hoard buriers.  We will need to find some way to remove them therefore without causing any damage.  I'm sure this will be possible but we might have to sacrifice the precise measurement of coin position we've done for all the others so far.

That's about it for now.  I'll blog again soon when we know more about the object and how its removal is going.