Most bricks nowadays are produced by mass production techniques. However some companies still produce small amounts of hand thrown bricks which gives handmade bricks their distinctive ' smiling ' pattern. After being formed the bricks are set aside to dry. Prior to firing most of the water content must be removed otherwise the bricks could explode if kilned too wet. This is done in drying houses with controlled temperature, draught and humidity.
Most kilns now are of the tunnel type.
As many as 3000 bricks are loaded onto moving carriages which enter the tunnel kiln at the cool end and move slowly forward through progressively increasing temperatures to the firing zone. They pass through it and into decreasing heat zones and emerge cooled. Though suited to mass production, by their very nature the kilns waste a lot of energy through heat losses along the kilns. In bricks the colours are predominantly natural and variations are through differing blends of clay. Fireclays usually produce the lighter colours such as buff and grey.