Hi Poppy, I don't have a solution, but I do suggest that you contact
Thompson enamel and speak to either Tom Ellis, or Bill Helwig. They
are both experts and hopefully they can help you.
Glass on Metal website (sponsored by Thompson Enamel), is also an
excellent source of and I believe you can submit your
question to them for help. I had a question some time ago and they
were very helpful. This is assuming you are working with Thompson
If you are working with the Japanese enamels, contact Coral Shaffer
(sp?), at Enamel Works in Seattle. Coral is an expert, and very very
Hope you find the answer to your problem.