Construction of Wood-Fired Kiln

Foundation The foundation consists of a concrete pad, for stability; a course of cinder block for elevation and heat buffer; and two courses of firebrick for further elevation and protection of the foundation. The Kiln Floor The floor is made up of four 1 x 18 x 24" silicon carbide shelves, which are covered by a 2" course of Insulating Fire Brick. Constructing the Walls The walls are coming to a height of 33" and ready for the arched roof.

Alternate Fireboxes The fireboxes are made up of a unique Detrick firebrick, designed for a hanging system. Cavities were filled with crushed IFB material. Kiln Floor–continued The idea is two-fold, first  to help protect the shelves from the dramatic temperature variation of the inner chamber and the fireboxes; and secondly, to help distribute weight evenly on these used and slightly damaged shelves. Side View: firebox and reinforcement steel. The foundation of the kiln is elevated using cinder block on edge. This effectively eases stoking.

Alternate Fireboxes Height of the fireboxes is at five courses to allow for a grate height of nine inches and plenty of room for a coal bed and adequate airflow. The Interior, Showing one inlet and the Exit Flue The flue is temporarily supported by two bricks while under construction. Arch is in place At this point preparations are being made for the steel framed reinforcement. Gaylen Peterson Potter/Instructor

The Chimney

The one element of the kiln that went through the most modification is the chimney. The initial plan indicated a 9x9" flue and the present configuration is 9x13". When Frederick Olsen says that the trick brick doesn't need to be moved during firing, it is absolutely true.

The passive damper system, picked up from other kiln designs, is completely unnecessary. An active damper would have been more useful for sealing up the kiln during the cool-down.

Nils Lou, in his book "The Art of Firing,"  proposes that a 9x9" exit is all that is ever necessary in kilns of any size. Secondly, he suggests a venturi effect takes place when you introduce a second 9x9" constriction in the chimney. I have taken note of this and made use of one of my passive damper bricks to support a brick and effectively collar the chimney down to the suggested 9x9." It is hard to tell if this makes any critical difference, but the most recent firing was even and did produce the best results to date.