An under-glaze decoration is hand-painted upon the raw and unbaked glaze.
Colour pigments (see Oxides) are gently laid upon the unbaked glaze and then fired in the kiln together with the glaze. The firing lasts about 12 hours at a high temperature of about 1,000° C (or 1,820° F). Colours then merge with the glaze and are thus very resistant to abrasion. This technique is called grand feu in French (″high fire”).