Structural Glazed Brick and Tile were first used in the US in the early 20th century. Many of these first glazed units were manufactured as “salt glazed” brick and tile. This glazing process utilized the use of regular table salt, NaCl, and reduced oxygen during the burning of the units. The salt was shovelled through small openings at the burner locations onto the gas fuel. The salt then vaporized and chemically mixed with the silicates of the body to form the salt glaze finish. This type of glazing has been discontinued for environmental reasons. Many salt glazed brick and tile buildings can still be seen today. You can recognize them by their wide color range-from a buff to an orange-brown color. The finish is transparent, showing the body color, which adds to the color variation. It also has small bumps in the glaze finish. Even though a true salt glaze is no longer available, Elgin Butler Company does offer many ceramic glazes in an attempt to match these old type glazes. Due to today’s tighter color control, you may need to use more than one color to achieve a wall with wide color variation.
Today the quality control standards for the ceramic glazed finishes are much more stringent. ASTM C-126 outlines the minimum standards for imperviousness, glaze opacity, hardness and abrasion, fading and chemical resistance. Under ASTM C-126, units must also have ratings of 0 smoke density, 0 flame spread, and 0 fuel contribution and emit no toxic fumes. ASTM C-1405 can be used for glazed brick.
Since brick has been used for thousands of years, the nomenclature for the structural tile industry was developed with brick in mind; however, it had to denote the type of shape and which sides of the units were glazed:
The “S” Series is a “Standard” brick, 2 1/4″ high and 1 B.E. (Brick Equivalent)
- The “D” Series is a “Double” brick, 5 1/16″ high and 2 B.E.
- Naturally the “T” Series is a “Triple” brick (3 B.E.), but keeps the 5 1/16″ height and added the extra B.E. onto the length of the unit, making a 6T unit nominally 12″ long instead of the normal 8″ brick length. (Remember 3 units that are 5 1/3″ high equals 16″ for coursing.)
Sizes continued to get bigger as time went by:
- The “W” Series is 8″ high and
- The “Y” Series is 12″ high.