I've been running a fingerprint jewellery business for about three years and although when I began I had some issues with the backs breaking off cufflinks, that was resolved and I've had no problems since then. Until recently that is! After making lots of cufflinks for Fathers' Day I had a few returns where the backs had broken off only in a different way from before. Rather than a clean break leaving a cufflink face that I could sand down and start again, this time small amounts of the silver from the back of the cufflink face had come away leaving a little pit. What was inside looked like unfired silver clay which suggested that the kiln had been underfiring. I spoke to the man at Prometheus and emailed the manufacturer in Turkey and was advised to recalibrate it and buy a new thermocouple which I did. Today I soldered a couple of cufflinks that I made since recalibrating and installing the new thermocouple. I gave them a good pull afterwards to make sure they were connected but again one of them broke and again taking away some of the silver. I was baffled and wondered if the cream coloured powdery looking interior that had been revealed really was unfired clay so I took a wire brush to it and after brushing it looked silver. So I'm really confused. At this point I don't feel I should take any more cufflink orders and considering they make up a substantial part of my sales I don't know if I can even carry on with the business unless I get to the bottom of this. If there are any experts out there or people who've had a similar experience I would be so grateful to hear from you! Many thanks