Flux

Chemicals, such as lead, soda, potash, used to lower the melting point ot the silica components of glass.

Chemicals such as soda, potash and lead, that lower the melting point of the main silica body of the batch, promoting fusion and flow. Flux added to colors of enamel, allowed them to melt before surface onto which they were applied to. Venetian glass, soda ash Bohemian, potash. Forest, wood ash. Lead crystal, lead oxide.