What is glass?
Glass is silica with various fluxes and metal oxides. Chemistry of Glass.
What is a flux?
In glass, a flux is a compound that lowers the melting point of silica and increases elasticity and working time. The most common fluxes used in glassmaking: Sodium Carbonate(commonly referred to as Soda Ash), Potassium Carbonate(Potash), Sodium Borate(or Borax), and Lead Carbonate. Using lead as a flux increases the weight and density of the glass as well as the optical clarity.
How it’s made
The first glass formed was obsidian created from molten rock from volcanoes. The rock contained Silica, various fluxing compounds and other metal oxides that gave it its color. When I make glass I start with an empty drum and a scale. I weigh out silica sand, add the fluxes and colorants and then I put the barrel on a roller to mix into a homogenous mixture. That mixture or batch will then get shoveled(Charged) into a 2400F furnace to melt in a crucible(clay bowl or container for the glass). 6-12 hours later the glass has cooked and is usable in its liquid state. It can be used like this or made into glass billets or cylindrical bars for later use.