search  current discussion  categories  kilns & firing - misc 

question for fire people

updated wed 8 sep 99


gari whelon on tue 7 sep 99

Hi folks:

I'm back from 6 weeks off list, potting holiday, folks up from Connecticut
and another firing of the Tozan.

Interesting questions and ideas.

My take on ash, and Though I've fired the Tozan several times I do not
consider myself anywhere near an expert, is that it takes both time and heat
to melt it.

The ideal, I think< is to have the ash collecting on the pots in the stage
when the flows in the kiln are more gentle and the heat is climbing, as the
heat increases,combustion is more complete and less ash is produced and or
the atmosphere is to turbulent to allow much ash to settle. As well, ash
deposited at the end of a firing often does not melt and you are left with a
gritty surface (not necesarily bad if you're after anagama effects, I
suspect some coffin or train kilns give this effect as well.

I had some wonderful pots out of the recent Tozan firing where even at about
cone 12 the ash on the fire side was fully melted and sprad over and down
the pots belly, the back side had much less in the way of runs and a
beautiful but less than complkete melt.

I suspect that if it was a bit cooler or a shorter firing the effects would
have been less dramatic.

Whats the concencus out there, am I correct in assuming that you don't want
too much ash at the end when its cooling?

Sure wish I could afford to go to the woodfiring conference at the end of
the month, I hope those of you who do will let us know all about it.

Getting back to Elizabeths original question, you might want to check out
the work of New Haven Connecticut's Stephen Rodriquez, he fires in gas and
uses raw ash and ash glaze on his pots and comes out with wonderful results,
might be what you're looking for. He had a spread in Studio Potter a few
years back when they did an article on Connecticut potters and I note they
have a back issue sale on right now.

Hope my ramblings are of help and not totally out of it.

Gari Whelon
Nanaimo, British Columbia

mourning the end of summer

iNTER>At 07:20 PM 9/6/99 -0500, you wrote:
>>I don't follow you.
>Good idea. I'm usually marching into a quagmire.
>But semiseriously, a cantrip is a spell, cast by a witch.
>To return to the idea Elizabeth brought up, before we were led astray by
>Gavin, I've often wondered why wood-firers don't often use blowers to
>increase the power of their fireboxes. I know that forced-air oil burners
>are much more powerful than natural draft oil burners like louver systems.
>In any case, I wonder why you couldn't pump ash into the end stages of a
>woodfiring, using something like a sawdust injection burner. I would think
>you'd have to be judicious, because if you pumped the ash in faster than
>the pot and glaze could absorb it, then you might end up with fuzzy pots.

Hank Murrow on tue 7 sep 99

>Fire people:
Don't laugh until you have read the whole question.

Good question Elizabeth; Think Time & Temperature. The beautiful results
achieved (most who've seen 'em say), in the U of Oregon, East Creek, &
Jewel Creek anagamas here in Oregon were because the surface of the pots
were sticky with heat and prior ash deposits. Time AT Temperature would be
even more true as a rule of thumb. Tried it the short way and got some real
CRUSTY ware. My suggestion for a woodfire cycle would be "get to C/10+
early and stay there for four+ days if you can. Stoking and not laughing,
Hank in Eugene

Steve Dalton on tue 7 sep 99

My understanding from what I've learned with my wood kiln is it'll take time
for the
ash to melt. You shouldn't have a problem with the salt though.
I have seen though where the potters will add the ash before they fire, but
the pots
came out chunky with ash.
Just remember the K.I.S.S. factor...Keep It Studiply Simple. I'm not saying
you are,
but the more factors you add can lead to more problems down the road.
Steve Dalton
> From: elizabeth priddy
> Subject: question for fire people
> Date: Mon, 6 Sep 1999 14:36:04 -0700
>Fire people:
>John Baymore's fascinating post on wood firing
>has set my brain on fire. Don't laugh until you
>have read the whole question.
>I have a question and I am willing to read all about it
>if someone can lead me to the source.
>I am basicly familiar with the theory on wood firing,
>so I don't think I can find the answer I need in
>wood firing 101 books, correct me if I am wrong.
>Is there such a thing as a kiln that you can fire to
>temperature and at peak temperature, cease adding fuel
>and drop a large load of ash onto the whole kiln full?
>I am assuming that the motion of the heat escaping
>if you open it at that time would be inclined to throw
>the ash back out like the big belching demons those
>wood kilns are, .
>But is there away to keep a chamber inside the
>perimiter of the roof that you could maybe slide
>something back and release the ashes onto the pots?
>If you built in a slot in the roof that would hold the
>ashes away from the pots by means of a kiln shelf, and
>then remove the kiln shelf, dropping the ashes as it
>pulls this logistically impossible? I am
>thinking of gas to make the heat and then the settling
>ash to make the coating. I am actually thinking about
>a mixture of ash and salt, but first things first.
>Or will the ash not become part of the glaze if you
>only introduce it when it is already molten?
>I already have mentioned that I am not a fire person,
>so please get up off the floor and stop laughing and answer slowly in very
basic terms.
>I speak from sincerity and experience, not authority...
>--== Sent via ==--
>Share what you know. Learn what you don't.