How to handle cracks in the enamel that reappear with each firing?
Some coloured enamels develop hairline cracks easily. This may be due to differences in tension between enamel and copper. But occasionally it seems impossible to prevent them from developing; then the ‘last resort’ is to cover the entire piece of work with a well washed soft flux and fire it. The flux fills the cracks (which ususally remain visible to the critical eye) and provides a nice, smooth top layer. An additional benefit is that the cracks no longer catch, and that the enamel will no longer chip off.