Morning all

Another little question - I use platinol to darken prints and text and polish back so the flat surface of charms are silver again. I always rinse the pieces well and soak in fresh pot of boiling water and bicarb for at least 15 mins, plus they get an ultrasonic bath. They go to customer looking perfect. However we keep getting people contact us a couple of days down the line saying a dark spot has developed on a silver area - seems to be happening more frequently lately even though have been extra careful in ensuring any rogue spots are removed. Is this just unavoidable or is there something else I could be doing to stop this? I thought the bicarb was meant to stop the reaction? Wondering if I have been sent a duff bag or something, my platinol is a few years old, don't know if that would make any difference? Thought of applying a dab of wax but would that stop a further reaction?

Any advice appreciated. Wish people wouldn't insist on us darkening things, would make life much easier and always think it cheapens the piece as they then remind of the gothic costume jewellery we used to buy from the local market as kids

Thanks

Mel