The biggest ultrasonic cleaning tank in the world

  

I was commissioned by Castrol to visit Kerry Ultrasonics and advise on products for use cleaning rescued artefacts from a sunken ship Mary Rose. I had the pleasant feeling of being off the leash as I bowled along in our new pool car, a Rover 2600. As Kerry was also owned by our parent Burmah I wasn’t even meeting a minder. Castrol had the attitude that technical staff were totally naïve in the ways of the world, should never be allowed with customers on their own, and were always to be accompanied by a minder. This had its attractive side as they were expected to entertain you, translate , arrange accommodation and the like.

It was a pleasant spring day and an enjoyable trip. I arrived to be met by a slightly worried looking guy who said their MD wanted to see me when I arrived. Aha I thought, a pleasantly formal greeting, possibly a gentle chat over a cup of tea. I had grown used to being treated with a great deal of respect when I made visits.

I duly presented myself to Gordon the MD, a short ,choleric man who greeted me as I  entered ”So you’re another of these useless wankers from Castrol”. I was absolutely gobsmacked as I was subjected to a quarter hour rant to the effect that we were a bunch of overpaid, idle, self abusers who couldn’t be expected to be of the slightest use.. As he wound down he could see that I was totally flummoxed and by degrees he explained in a more kindly way that I was to have the problem explained by the minion I had met and I was then to present myself again in a week’s time with the answer to their needs

I duly met with said minion and things became somewhat clearer. The “Mary Rose” was a 16^th century warship  ( Henry VIII’s flagship ) which sank in the Solent in 1545 and had recently been recovered along with a great many artefacts from the period. The recovery operation had Prince Charles as patron who had turned to Margaret Thatcher, the then Prime Minister for help in finding supporters. She in turn had talked to her husband Denis Thatcher who was a director of Burmah. In turn he had talked to Gordon. Gordon had expansively said they would donate an ultrasonic cleaning tank to the conservation operation having in mind a typical small tank.

Now ultrasonic cleaning tanks were typically quite small, twenty litres quite normal and a hundred litres would be quite substantial. However the conservation operation had recovered a number of large wooden gun carriages and needed a tank which could accommodate these. This meant a tank of 2000 litre capacity. This was a very expensive, unique piece of kit which Gordon now felt committed to donating despite his unhappiness at the cost.

I was also to find another reason for his jaundiced attitude to Castrol. Years previously ( before my time ) Castrol had become somewhat persuaded that ultrasonic cleaning was the future. A series of products had been cobbled together without much thought and with very little success. Nevertheless Kerry had become obligated to try and sell these products which they came to regard as a millstone around their necks..

Fortunately I could easily understand the immediate technical problem and was able in a week to revisit with an acceptable product. Castrol was donating the product to the “Mary Rose” trust. It was pleasant that the development was quick and easy as we didn’t even have our own tank to test.

To digress we later bought one which became extremely useful on open days. We did a demonstration of jewellery cleaning particularly rings. It was always gratifying to see the amount of accumulated crud removed in seconds. Our joking introduction always was along the lines that any jewels removed and falling to the bottom of the tank were ours. None ever were, of course. Rings, particularly complex ones, collect a lot of dirt and dead skin cells.

The Kerry test was in a way very simple. The product solution filled the test tank and it had to “couple” as the jargon had it- that is it had to wet the ultrasonic transducer and travel through the solution to the item to be cleaned. Success was indicated by a steady  hiss, failure by a horrible screech varying  randomly in pitch.  Successful transmission shredded aluminium foil.

I was to spend an interesting day visiting the warehouse storing the artefacts from the ship. The wood had become complete soaked in seawater with iron salts deposited in the wood fibres. Drying was disastrous and conservation required the iron salts and water to be removed and replaced by a thick liquid such as a type of antifreeze. Drying alone just gave a distorted and unstable residue as a lot of the internal structure of the wood had rotted over the years.

Although very interesting it was 250  miles from home at Wilmslow to Portsmouth where the Trust was based and I attempted this in a one very long day. I remember taking a break south of Oxford in late evening and thinking, with sinking heart, only another 150 miles to go. The pool car wasn’t available and I had to use my own.

I was too junior to go to the formal handover ceremony. I was told that there was a horrible few seconds of screeching before the monster tank settled down to a steady hiss to the profound relief of the Castrol dignitaries present.

I later became quite friendly with Kerry staff who allowed me some rare privileges.  However I never forgot the shock of my introduction.. I also learned that the technology Kerry used ( Piezoelectric) was unsuitable for large tanks and the people who did make larger tanks in the US used magnetostrictrive technology