Dave is Supervisor of the assaying department. Dave is another one of our staff who has been with us for many years. Dave started here 34 years ago in the ‘Silver Drawing’ department.
Describe a typical working day
We run quality controls on our XRF machines before we start work to ensure that we are measuring accurately. If we have a lot of urgent packets, I join the team testing items with a touchstone or on the XRF.
Customers probably don’t realise that we still use touchstones – the method that has been used for more than 700 years – it can be a really quick way of identifying problems when you have a lot of articles to test.
The rest of my day is taken up with admin – dealing with failed packets, speaking to customers and answering queries. Sometimes we take samples to test in the laboratory.
What’s your favourite type of packet?
When everything is exactly as expected, particularly if it’s a customer we know well. It’s easy to test, quick and all to the correct standard.
What’s your favourite type of metal?
It’s definitely silver. I started in the ‘Silver Drawing’ department in 1979 and we used to test all sorts of items - everything was touch-tested, sampled (where we scraped a bit off) and we used to see such a variety, particularly compared to the ‘Gold Drawing’ department, where we only really saw items of jewellery.
How did the introduction of XRF machines change your department?
XRF is a simple technique that can be taught easily. It is a low level x-ray machine that measures the components of an item, giving us a percentage content. It makes run of the mill testing much more efficient. We do find problems that we would have previously been unaware of – so it has its own challenges and we are always looking for new techniques to help us to determine whether there is a genuine problem, or a misinterpretation of the data.
Where the XRF is invaluable is in detecting things that might previously have been missed. For example, some manufacturers include a copper layer between a precious metal and plating. The XRF can measure a very fine flash coating and identify it. Our job is to decide if the reading is substandard silver or copper in rose gold plating or if there is a copper layer underneath and sometimes we do have to remove a very small area of plating to uncover the copper but with the XRF this can be almost invisible to the naked eye.