| Firing
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The next step is burning or firing the green brick. The green brick pass through the long length of the kiln on a continuous procession of cars moving on rails, much like a small railroad train. The continuous tunnel kiln employs a combination of vertical and horizontal drafts. The preheating, burning and cooling is done in zones varying in temperatures up to 2,000 degrees. In this type of kiln, closer temperature control is possible and less handling of the green brick results in better quality products.
When the green brick enters the kiln, the manufacturer determines the type of firing required to produce the desired range of color. If a range of clear burn color is wanted, a straight burn from start to finish produces the desired result. The only color variations being the extremes of dark color nearest the fire or in the crown on the kiln and the light color at the bottom where the brick have the lowest temperature. The remainder of the brick will have medium tones. However, if the kiln is designated to be flashed, the dampers are regulated at the end of the burn to cut off the air and subject the brick to a reducing fire, thus bringing out the blacks, blues, browns, etc. which make up a flashed range.
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inside tunnel kiln
firing brick
brick inside kiln
fired brick showing ranges of colors
fired brick clearburn
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