Cristallo

The invention of Cristallo glass is attributed to Angelo Barovier around 1450.

Materials

In addition to common glass making materials, manganese, quartz pebbles, and alume catino, a particularly suitable form of soda ash, are used in the making of cristallo glass.

Rather than using common sand, crushed quartz pebbles were used instead. The quartz pebbles were typically from the Ticino and the Adige rivers. The quartz pebbles went through a rigorous screening process before being selected for use in cristallo production. The quartz pebbles had to be free of yellow and black veins and also had to be able to produce sparks when struck with steel.

The quartz pebbles which passed the selection process were heated to the point where the stones began to glow, then placed into cold water. Then the pebbles were crushed and ground.

The typical flux used in the production of cristallo was called alume catino. Alume catino was derived from the ash of the salsola soda and salsola kali bushes that grew in the Levantine coastal region. It was found to contain high and constant amounts of sodium and calcium carbonates, necessary to make workable and chemically stable glass.

The ash of the plants was carefully sieved and placed into water to be gently boiled with constant mixing. Then the ashen mixture was placed into shallow pans to be dried. The alume catino would repeatedly undergo the boiling and drying process until all of the salt was extracted from the ashes.