At very high temperatures, the colours of cloisonné materials fade and tarnish.
In the olden days, as metals and ceramic were not pure, impurity bubbles were liable to form and burst, thus ruining the cloisonné work. Numerous failed attempts would then precede a successful cloisonné piece. Therefore, cloisonné items were very expensive. Thanks to Chinese expertise in porcelain making, the mastery of firing temperatures and colours in cloisonné making developed. Indeed, this art has been so exquisitely refined since the Ming Dynasty that it has become one of the five disciplines of Chinese traditional fine art.
Today, if temperature and purity are no longer a source of trouble, the disappearance of artistic cloisonné making, in itself, is. Meanwhile, ordinary, worthless painted ceramics are marketed so as to compete with genuine cloisonné pieces like ours.