Venetian glass is sodic, in the ancient Mediterranean tradition. This means that silica, which is a type of sand that becomes glass when it melts, is combined with soda which lowers its fusion temperature. Potassium, which may be an alternative to soda, and is typically used in Nordic countries, gives a brilliant glass suitable for cold-work and engraving, like English leaded glass, but not appropriate to the complex hot work typical of Venetian glass. The raw materials are mixed in the evening, at the end of the glassmasters' working day. A stabilizing element, calcium carbonate for example, the bleaching or coloring agents, and opaquing agents ìf required, are added to the two basic raw materials.A reverberatory furnace, in which the fire below the pots heats the vault of the fusion chamber and attacks the mixture from above and below, melts the raw materials so that in the morning the glassworkers find the molten material ready to shape.The work team is constituted by a "piazza", coordinated by the maestro and completed by the serventi and garzoni, who have mastered the various hot work techniques. The piece in glass will successively be finished in the cold work shop, where expert grinders will proceed to polish it or finish it in other characteristic finishes at the wheel.Figurative engraving is done in independent workshops, at the hands of highly specialized decorators. If the decoration is however to be done with enamel paints, the object must proceed to a workshop specialized in painting and firing the enamel. Murano also produces semi-finished materials for lamp-work or re-use in furnaces: these are mostly glass rods, but also ground glass and fragments of plane glass. Glass rod is also used for the lamp-work figures and multicoloured beads.