Jeff Ferguson on fri 25 dec 98
I need help with surface flashing in my wood kiln. I don,t like to glaze my
wood fired work. Idon't have a clay mixer so I am limited to ready mixed clay.
We fire with oak for 8 hour minimum. I would like help in anyway to get nice
flashing. My attraction is to nice warm surfaces of wood fired pots. Thanks
and Merry Christmas.
Don & Isao Morrill on sat 26 dec 98
At 17:33 12/25/98 EST, you wrote:
>----------------------------Original message----------------------------
>I need help with surface flashing in my wood kiln. I don,t like to glaze my
>wood fired work. Idon't have a clay mixer so I am limited to ready mixed
clay.
>We fire with oak for 8 hour minimum. I would like help in anyway to get nice
>flashing. My attraction is to nice warm surfaces of wood fired pots. Thanks
>and Merry Christmas.
>
>Jeff,Why fire with oak..unless that's all you have. Our experience,(and
that of many) is that hardwoods have very short flames although intense
heat, Soft woods,such as pine,(in Japan, 'Aka Matsu) spruce or fir have
very long flames which work their way through the pots,giving-up and
burning their gases,probably at a lower temperature and allowing the
mineral deposits. The longer the firing the greater the deposit of the
minerals trapped in the wood as a part of growth. All o our wood-fired
pieces show this deposi. Once piece in particular by Rikio Hashimoto of
Ariake,Kyushu(good friend and former student with whom we have fired many
times) sent us a piece several years ago with a fine glazed deposit,in
places nearly 3mm thick. This was fired in an Ana-gama for over 144 hours
using split pieces of old,(shame!) Japanese farmhouses. In New
Brunswick,Canada we fired our 300cft. kiln for seven days...cooledit and
didn't care for the effect. Fired again for six days and liked the effect.
We used cut up slab wood,mostly spruce and with a great deal of bark adhering.
Isao & Don Morrill
clennell on sat 26 dec 98
>----------------------------Original message----------------------------
>I need help with surface flashing in my wood kiln. I don,t like to glaze my
>wood fired work. Idon't have a clay mixer so I am limited to ready mixed clay.
>We fire with oak for 8 hour minimum. I would like help in anyway to get nice
>flashing. My attraction is to nice warm surfaces of wood fired pots. Thanks
>and Merry Christmas.
I think if you are ambitous enough to build and fire a wood kiln you can
make some great clay. You are not limited to the boxed variety. Here is
the formula for a a beauty body for wood firing.
To make it , mix the ingredients as a thick slip and pour it into some
panty hose or a some good cotton pillowcases. Hang to dry. Wedge right in
the bag and throw. If you do a neat hanging job of it and your neighbour
knows you just bought a Stihl 026 he may think you are the Chainsaw
murderer.
Clean and scrub the pantyhose with warm water and you are all set for a
night of cross dressing.
A flashing body:
Foundry Hill Cream 35
Helmar Kaolin 45
G-200 20
Silica Sand 10
If you insist that you don't want to make the body, why not just dip the
pots in this slip?
Good luck
Tony
Clennell
4545 King Street RR# 1
Beamsville, Ontario Canada L0R 1B0
phone (905) 563-9382
fax (905) 563-9382
e mail clennell@bestnet.org
Bill Amsterlaw on sun 27 dec 98
Hi Clayart:
Jeff Ferguson wrote:
<< I need help with surface flashing in my wood kiln. I don't like to glaze
my
wood fired work. I don't have a clay mixer so I am limited to ready mixed
clay.
We fire with oak for 8 hour minimum. I would like help in anyway to get nice
flashing. >>
I have a lot of interest in firing with wood - but no personal experience.
All I know is stuff I have read.
From reading your post, it dawned on me that the great efficiency of a
fast-fire wood kiln makes it possible to burn wood like oak, which has a
long, slow burn with a lot of coals. Also, you probably can use use larger
logs - avoid a lot of wood splitting. However, as you have observed, just
getting to temperature doesn't necessarily get you the surface you want.
How you get there makes a difference. Is there something to be gained from
the labor of throwing in a zillion skinny hot-burning pine sticks when a
modest number of oak logs will get you to temperature?
There is a difference in the chemical composition of the ash from different
types of trees. The type of wood you burn makes a big difference both in
the composition of the fly ash as well as volatile substances in the kiln
atmosphere ... which result in differences in what hits the ware downstream.
Also the longer the firing, the more time there is for stuff to deposit.
Comparing the analysis of oak ash vs pine ash (taken from "Ash Glazes" by
Phil Rogers - below), pine ash contains twice as much potassium, twice as
much iron, and 50 times as much manganese. This means to me that pine ash
ought to be a much more powerful flux and contribute quite a lot more
colorant material - ie, should result in more "flashing". ( I also note
something really amazing on the same table in Phil Rogers book: Spruce ash
is 23% MnO!)
Na2O Oak 9.4% Pine 9.1%
K2O Oak 14.4% Pine 28.0%
MgO Oak 12.4% Pine 6.7%
CaO Oak 31.0% Pine 26.4%
CuO Oak 0.1% Pine 0%
MnO Oak 0.1% Pine 5.3%
Al2O3 Oak 0.1% Pine 0.5%
SiO2 Oak 15.8% Pine 10.6%
P2O5 Oak 14.2% Pine 9.3%
Fe2O3 Oak 2.5% Pine 4.2%
- Bill Amsterlaw (wamster@slic.com)
Plattsburgh, NY
Marcia Selsor on mon 28 dec 98
Dear Jeff and Bill,
I fired an "Olson Fast Fire Wood Kiln" in Latvia in 1991. Many of the
pieces from that firing were in the Eastern European Ceramics Show at
the Clay Studio in Phila. in 1994. The kiln was fired unevenly with
oxidized areas. This could be because of the large size of zome of the
sculptures and the stacking. We fired with pine (somewhat wet). -dried
it lath by lath around the firebox.
It seems that firing with oak would be difficult because it is a slow
burning wood. I always have split pine into lath size pieces to make it
combust quickly. Fired alot of wood raku this way. -very fast.
Marci in Montana
>
> Jeff Ferguson wrote:
> << I need help with surface flashing in my wood kiln. I don't like to glaze
> my
> wood fired work. I don't have a clay mixer so I am limited to ready mixed
> clay.
> We fire with oak for 8 hour minimum. I would like help in anyway to get nice
> flashing. >>
>
> I have a lot of interest in firing with wood - but no personal experience.
> All I know is stuff I have read.
>
> >From reading your post, it dawned on me that the great efficiency of a
> fast-fire wood kiln makes it possible to burn wood like oak, which has a
> long, slow burn with a lot of coals. Also, you probably can use use larger
> logs - avoid a lot of wood splitting. However, as you have observed, just
> getting to temperature doesn't necessarily get you the surface you want.
> How you get there makes a difference. Is there something to be gained from
> the labor of throwing in a zillion skinny hot-burning pine sticks when a
> modest number of oak logs will get you to temperature?
>
> There is a difference in the chemical composition of the ash from different
> types of trees. The type of wood you burn makes a big difference both in
> the composition of the fly ash as well as volatile substances in the kiln
> atmosphere ... which result in differences in what hits the ware downstream.
> Also the longer the firing, the more time there is for stuff to deposit.
>
> Comparing the analysis of oak ash vs pine ash (taken from "Ash Glazes" by
> Phil Rogers - below), pine ash contains twice as much potassium, twice as
> much iron, and 50 times as much manganese. This means to me that pine ash
> ought to be a much more powerful flux and contribute quite a lot more
> colorant material - ie, should result in more "flashing". ( I also note
> something really amazing on the same table in Phil Rogers book: Spruce ash
> is 23% MnO!)
>
> Na2O Oak 9.4% Pine 9.1%
> K2O Oak 14.4% Pine 28.0%
> MgO Oak 12.4% Pine 6.7%
> CaO Oak 31.0% Pine 26.4%
> CuO Oak 0.1% Pine 0%
> MnO Oak 0.1% Pine 5.3%
>
> Al2O3 Oak 0.1% Pine 0.5%
>
> SiO2 Oak 15.8% Pine 10.6%
> P2O5 Oak 14.2% Pine 9.3%
> Fe2O3 Oak 2.5% Pine 4.2%
>
> - Bill Amsterlaw (wamster@slic.com)
> Plattsburgh, NY
--
Marcia Selsor
mjbmls@imt.net
http://www.imt.net/~mjbmls
http://www.imt.net/~mjbmls/spain99.html
Jeff Ferguson on sun 3 jan 99
Bill
Thanks for the input. My next firing may be with all pine . I am getting ash
build up with runs of glass but not anything else that excites me other the
fun I am having with the process. I only have pine and oak and neither as any
bark where i think the good stuff may be. The work we glazed came out
wonderful but I feel that is what the gas kiln is best used for. Thats what
I hate about this game , there is just to many options for us cover.so I do
what is fun.
Jeff
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