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hard brick/soft brick

updated sat 23 dec 00

 

John Britt on fri 22 dec 00


Hello,

Hard brick kilns are still a very viable option. They are extremely
durable. They heat up and cool down slowly, which has beautiful effects
on glazes. Everyone who loves old Chinese pots should remember that they
were fired in hard brick kilns with long cycles. Fuel savings in only
one aspect to consider. Sometimes the final product is actually worth
the time, effort and fuel that you use.

Hard bricks are unparalleled in salt and soda kilns. Regardless of how
much ITC you apply, a hard brick salt kiln will out last a soft brick
kiln. Probably by two to three times. We had a soft brick / ITC
salt/soda kiln here at Penland, before I came. And I believe it lasted
about 2 years before it had to be torn down to be rebuilt as a hard brick
salt/soda kiln. (I have to talk to Tracy D. about the exact details if
you need them.) Of course, the kilns here get the maximum heavy use!

As for economics, although soft bricks use less fuel to fire, they are
generally two to three times more expensive than hard bricks. (Varies
according to supplier.) And ITC is very, very expensive. I remember it
being about $135.00 a gallon. And frankly it is not magic. It cannot
suspend the laws of nature, it cannot stop the laws of entropy from
operating. Salt is extremely corrosive.

There are great reasons to build a soft brick kiln and great reasons to
build a hard brick kiln. Hard bricks are not out of date, yet.

If you are doing very light soda firing then soft brick and ITC may do
the job just fine. Or if you fire very infrequently. If you are using
a lot of soda and/or salt then I would definitely go with hard brick
unless you like building kilns. Fast firing, quick testing, raku or
bisque firing are all great reasons to use soft brick kilns.

Get a lot of opinions.

Thanks,

John Britt
Penland Clay


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