Most alkali metal oxides M2O (M = Li, Na, K, Rb) crystallise in the antifluorite structure.

A third much less known method involves heating sodium metal with iron(III) oxide (rust): the reaction should be done in an inert atmosphere to avoid the reaction of sodium with the air instead.

Furthermore, such glasses are not made from sodium oxide, but the equivalent of Na2O is added in the form of "soda" (sodium carbonate), which loses carbon dioxide at high temperatures: A typical manufactured glass contains around 15% sodium oxide, 70% silica (silicon dioxide), and 9% lime (calcium oxide).

The sodium carbonate "soda" serves as a flux to lower the temperature at which the silica mixture melts.

Such soda-lime glass has a much lower melting temperature than pure silica and has slightly higher elasticity.