An excerpt from the law n°82-22, of 2-25-1982, journal officiel of the french Republique

The terms « enamel »; or « enamels » are used only in reference to the vitrifiable products of fusing, vitrification or frittage of mineral substances. Such products are destined to form, whether in one or more layers, a vitreous coating baked at a temperatuer of at least 500° C”.