Vitreous refers to a surface material on some plumbing fixtures derived from or consisting of glass. It is low in porosity and is translucent
---> see also: "Vitreous" is in the NAICSCode "327111" (Vitreous China Plumbing Fixture and China and Earthenware Bathroom Accessories ManufacturingVitreous China Plumbing Fixture and China and Earthenware Bathroom Accessories Manufacturing)