Unglazed porcelain – There is no glazing or any other coating applied to the tile. Their color is the same on the face of the tile as it is on the back resulting in very durable tiles that do not show the effects of heavy traffic. The most common unglazed tiles are the red quarry tiles or the granite looking porcelain ceramic tiles used in heavy commercial areas. Historic matches to the original tiles made from 1890 - 1930's. Subway Ceramic floor tiles are made of the highest quality unglazed porcelain and carefully arranged on a fiber mesh as one square foot sheets. A complimentary black hex is also in stock in both sizes and available by the sheet for creating borders and accent designs. Subway Ceramics offers vintage tile is 3/8" thick, with a flat surface and square edges. The Subway Ceramics collection of traditional subway tile, moldings and accessories.