Under-fired 2020 Flux Enamel on Copper

In my last post, I mentioned that there is a very large difference in appearance between under-fired and fully-fired clear enamel on copper. In this example, I used Thompson 2020 flux over copper.

When the under-fired piece came out of the kiln, the copper oxides were black and then cooled to the red colour captured in the photo. If I fully fire the copper, the oxides will be absorbed into the glass and the metal will appear bright once more.

Left: Under-fired 2020 flux over copper                                                                                                             Right: Fully-fired 2020 flux over copper