Vitreous china

The coating makes the porcelain tougher, denser, and shinier, and it is a common choice for items such as toilets and sink basins.

[7] The low occurrence is due to vitreous china’s fragility when exposed to blunt force from crockery and other kitchen items.

Vitreous china, like other enamels, is a glass-particulate composite, meaning it is glass (50-70 wt%) with non-silicate particles strewn about it that give it different properties.

[8] Included in the vitreous enamel mixture is clay, which helps hold it all together and gives the necessary flexibility to form it into shape during firing, quartz which reduces shrinkage, and feldspar which increases the liquidity of the mixture when fired into its vitreous phase; this ensures low porosity in the final product.

[11] Not all of the quartz and feldspar liquify during firing, and so some of it remains as “relict” (its pre-firing powder form) in the final vitrified product.

In covering their porcelain substrate, vitreous china gives anti-corrosive properties and helps against weathering and heat.

[8][11] Such properties depend on the particles in vitreous china's glass mixture, which can vary in type, size (1-50μm), distribution or shape.