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.

Alternate Fireboxes
The fireboxes are made up of a unique Detrick firebrick, designed for a hanging system. Cavities were filled with crushed IFB material.

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 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.

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.

The Interior, Showing one inlet and the Exit Flue
The flue is temporarily supported by two bricks while under construction.

Constructing the Walls
The walls are coming to a height of 33" and ready for the arched roof.

Side View: firebox and reinforcement steel.
The foundation of the kiln is elevated using cinder block on edge. This effectively eases stoking.

Sprung Arch is in place
At this point preparations are being made for the steel framed reinforcement.

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." Further use of two other bricks as an active damper, creates back pressure and helps to even out the temperatures from top to bottom.

Gaylen Peterson

Potter/Instructor