These large fireclay crucibles are entirely hand-made by Lalique potters. Once dried, the master potter moistens them in order to smooth them perfectly. The crucibles must not give off dust: grains could get into the glowing mass of the molten crystal and soil it. The crucibles can only be used after several months of drying in a hot chamber. They must not have any defects as they are subjected to very high temperatures when placed in the pot furnace. They have a shelf life of a few weeks, after which they must be replaced.