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woodfire glazes and claybodys?

updated fri 16 aug 02

 

rohde on tue 13 feb 01


i have 3 different Questions for all of you....

1. is i am building a fast fire wood kiln and i need to know what the =
flex bored is used for and do i really need it??????

2. i need woodfire glazes? =20
ash glazes
etc......

3. and are their any claybodys type that work really well in woodfire.
if so what do i need to make them...


thanks=20
much

andy

Hank Murrow on tue 13 feb 01


>Andy wrote;

>i have 3 different Questions for all of you....
>
>1. is i am building a fast fire wood kiln and i need to know what the flex
>bored is used for and do i really need it??????
>
>2. i need woodfire glazes?
> ash glazes
> etc......
>
>3. and are their any claybodys type that work really well in woodfire.
> if so what do i need to make them...


Hank replies;

1> The flex board you refer to (or any other nonpermeable board or
metal cladding WILL reduce air filtration into the kiln. Reason enough in
my opinion. It will not add any effective insulation.

2> Get Ian Currie's book, "Revealing Glazes"; this approach works
for found materials as well as bought materials.

3> Claybodies which are low in alumina and high in silica seem to
take the ash better. Also good for color to include clays with higher
titania and (up to a point....say 1%) iron.

4> MY question is, "How did you get so far into it with so little
preparation?"

In any case, Cheers, Hank in Eugene

mudlark on tue 13 feb 01


rohde wrote:

> i have 3 different Questions for all of you....
>
> 1. is i am building a fast fire wood kiln and i need to know what the flex bored is used for and do i really need it??????
> Probably not. Where is it used?
> 2. i need woodfire glazes?
> ash glazes
> etc......
> I've always salted and used celedons. I glaze with a wide temp. range
> 3. and are their any claybodys type that work really well in woodfire.
> if so what do i need to make them... Stoneware what temp?
>
> thanks
> much
>
> andy
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
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> You may look at the archives for the list or change your subscription
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Louis Katz on tue 13 feb 01


I would suggest former clayarter Jack Troy's book on wood firing.
In addition to his suggestions I would add very coarse claybodies, but in my limited experience fastfire woodkilns fire more
like gas than heavy ashed kilns.
Louis

rohde wrote:

> i have 3 different Questions for all of you....
>
> 1. is i am building a fast fire wood kiln and i need to know what the flex bored is used for and do i really need it??????
>
> 2. i need woodfire glazes?
> ash glazes
> etc......
>
> 3. and are their any claybodys type that work really well in woodfire.
> if so what do i need to make them...
>
> thanks
> much
>
> andy
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at melpots@pclink.com.

Anthony Allison on wed 14 feb 01


Dear Andy,

I have a fast fire kiln i built. It was fired twice a month for like 7
years. I rebuilt it twice. The first time cause i couldnt get it above cone
4 after several firings and times involviong 24 hours.. I remedied that by
using a bigger taller chimney, and by insulating the kiln with a 6 inch
layer of sand. First firing we hit cone 10 -11 in 8 hours.

The second problem was the flat foor is a poor design and it sagged and
caved in very quickly no matter what we tried using for the floor. Also ,the
iron grates were shot in one firing. Second rebuild involved building arches
over the fireboxes to keep the floor from falling in. We quit using iron
grates. We just feed the wood in 8 foot lengths instead of cutting it into
smaller lengths. Later, as a luxury, we also installed an oil drip system
for assist when wood quality was poor- like during heavy rains or snow. We
control the oil flow from 55 gallon drums with a simple needle valve, and
let the oil flow down a steel pipe onto a piece of sheet metal on top of the
coals. A damper built in as the flu goes to the chimney helped in
controlling the kiln, and shutting down at the end of a firing.

The interesting thing about wood fire is how it affects regular glazes. You
can try all your regular cone 10 glazes. You may find you will need to
adjust them for the degree of matte or gloss you prefer, as a wood fire
kiln i believe, due to the fluxing action of vaporized ash vapors, gives
cone readings which are different from if you are accostomed to firing with
gas. A fairly matte glaze at cone 10 wood is very shiny and overfired in a
cone 10 gas firing i have found.

After you fire the kiln a few times you will have so much ash that making
ash glazes is a really smart way to utilize that asset. The greatest action
was where the flames exited the kiln at the flu to the chimney. One word of
advice is to start your kiln with charcoal the night before to let
everything heat up slowly. Trying to start with a wood fire right off
usually breaks a lot of pots. It is hard to start slow with a gentle flame.

Good luck,

tony

i have 3 different Questions for all of you....

1. is i am building a fast fire wood kiln and i need to know what the flex
bored is used for and do i really need it??????

2. i need woodfire glazes?
ash glazes
etc......

3. and are their any claybodys type that work really well in woodfire.
if so what do i need to make them...


thanks
much

andy

____________________________________________________________________________
__
Send postings to clayart@lsv.ceramics.org

You may look at the archives for the list or change your subscription
settings from http://www.ceramics.org/clayart/

Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.

Mark & Sylvia Mondloch on wed 14 feb 01


>I have a fast fire kiln i built... The second problem was the flat foor is
a poor design and it sagged >and caved in very quickly no matter what we
tried using for the floor. Second rebuild involved >building arches over
the fireboxes to keep the floor from falling in.

Interesting. I wondered if the flat floors would hold up over extended time.
My Phoenix (fast-fire, cross-draft) has an arch over the single firebox
under the kiln -lookin a bit rough but still there after 20 years.

>Also ,the iron grates were shot in one firing.

I also found light-weight iron grates to not hold up. Then hubby found 2"
rebars and we put a row of supporting bricks( the long way) down the center
of the 24" wide firebox. It made a world of difference. The grates now last
maybe 15 plus firings. I don't think I could fire mine efficiently without
grates.

>Trying to start with a wood fire right off usually breaks a lot of pots

Yea. Rather then nursing a little fire at the firebox mouth, I use our
kerosene torpedo heater over-night before a firing. For a few dollars it
prevents alot of stress.
Sylvia

Mark & Sylvia Mondloch
Silver Creek Pottery & Forge
W6725 Hwy 144
Random Lake, WI 53075

silvercreek@execpc.com
http://www.execpc.com/silvercreek

Tim Welch on fri 16 aug 02


It is my understanding that ash heated to a high temperature such as the
typed produced in a wood kiln is worthless for use in ash glazes. That is
just my understanding though, it is worth a shot. My choice is hardwood
ash from my fireplace or creating it using the ash from the branches of a
hardwood such as oak. The composition of the ash produced from branches
is supposed to be better suited for ash glazes, perhaps a matter of
opinion. Take care then.

Tim Welch - Oregon