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salt kiln stack construction

updated sat 31 aug 96


William Brouillard on fri 23 aug 96

Salt kiln stack construction.

The height and interior cross sectional area of the stack will be determined

by at least three things.

1. The type of burner system you are using. Forced air systems require

less in terms of height than do natural draft systems. Natural draft systems

depend on stack height to develop velocity in the draft.

2. Local building, zoning or fire codes which may specify certain types

of construct or construction materials. You should check with your local

codes or Fire Marshall. It may be that your stack has to extend a certain

height above your roof line or that it can not be loose brick construction

and must be mortared.

3. Salt firing is a vapor process that is usually done at high temperature.

The exhaust gases will be very hot and very corrosive. That may eliminate

some materials that could be used on other types of kilns. Chimney liners

and red brick are probable out of the question.

A ten foot stack with a 9" x 9" flue area would use approx. 300 standard

size firebricks.

Any low duty firebrick should do the job. Scrap brick could be used in

the upper third of the stack where the heat and corrosive effects of the

vapor will be less..

Many potter lay the brick for the stack dry or with a 50/50 mix of fireclay

and sand. It fills the gaps but comes off easily when rebuilding.

The base of the stack should be two courses thick if laid dry. It will be

more stable and provide a better heat differential for the stack. I usually

put insulation brick as the outside layer to protect students from being

burned on the hot firebrick and to increase the heat differential which

increases the velocity of the flue gasses. A frame of angle iron will hold

the loose bricks in place and provide stability for the stack.

william brouillard
1011 literary road