Stannic acid is produced as byproduct.

"Stannic acid" refers to hydrated tin dioxide, SnO, which is also called "stannic hydroxide."

Stannous hydroxide is easily oxidized to stannic acid (Sn(OH)) by air since tin is often found in oxidation state +4.

Stannic acid (Sn(OH)), the formal precursor to stannates does not exist and is actually a hydrate of SnO.

For glaze use only one tin compound, tin (IV) oxide Tin dioxide (SnO), and also called stannic acid, is commercially exploited.

Hydrous forms of SnO have been described in the past as stannic acids, although such materials appear to be hydrated particles of SnO where the composition reflects the particle size.