Ceramic tile comes in two forms: glazed, the most common, and unglazed. Glazed tile can have a white or clay-colored body onto which the pigmented glaze is fixed to the tile when fired under high heat. Glazed tiles are hard and non-porous with a surface that is stain, scratch and fire resistant. They won’t fade in the sunlight and are easy to clean. Glazed tiles are available in high glass, matte and slip resistant finishes. A drawback to glazed tile is that the glaze of color, or finish, does not run through the body of the tile. If a tile is chipped, the white or clay-colored body of the tile shows through.
Unglazed tiles include red quarry and terracotta tiles and porcelain tiles. Porcelain is a relative newcomer. Because these tiles are porcelain through and through, they are extremely hard and virtually impervious to moisture. This makes them the most durable member of the ceramic tile family. Unglazed porcelain tile is the same color throughout, so chips don’t show as badly as when a glazed tile is damaged. Porcelain tiles are, themselves, being used as the body for many glazed tiles--especially those that replicate natural or tumbled stone in the larger size tiles. Manufacturers who glaze on porcelain base are choosing a porcelain body color that approximates the color of the glaze so that the inevitable chip or ding will be as inconspicuous as possible. Porcelain tile generally costs more than ceramic tile, but is less than stone--to which it is technically superior.

The firing process for any tile can result in dimensional variations between individual tiles. This is less of a problem with machine made tiles, but hand made tiles--especially the imported ones--are susceptible to these variations. So always make sure you buy from the same lot and color number. As with any flooring product you select, buy almost 10% more than you will need. This will cover normal installation wastage and leave some extra tiles if you need to make repairs later. If your floor requires a lot of tiles to be cut to fit odd spaces, increase your overage to 15%

It’s impossible to talk about tile without talking about grout--that sand-based material that goes between the tiles. Because grout is available in many colors, it becomes a design element in any installation. In that regard, choosing a grout that approximates the tile color results in a floor where the grout lines are less obvious. Some people like the grid effect of contrasting grout lines--the natural result of using a light grout with a dark tile or vice versa.