Sumi von Dassow on fri 21 may 10
Paul
I can get mine to fire quite evenly if I am careful with the firing
schedule but I'm firing to cone 7, not 10 and my kiln is 27 cubic feet.
It's more or less the same configuration, a car kiln with two burners
from the back. If I reduce too heavily it gets hotter at the bottom than
the top. If the bottom does start racing ahead I turn down the gas
pressure and close the damper a bit to allow the heat to naturally rise
to the top.
It doesn't have bag walls except for a row of bricks at each edge of the
bottom shelf which I always stack 9.5" high. Maybe it's the size of
yours that makes it impossible.
Sumi
> i have a downdraft gas/oil kiln that is about 70 cu.ft. with forced air =
burners. It is a car kiln with two burners that come in from the back. I ha=
ve adjusted the bagwall numerous times (and at first I did not even use one=
) but have never had a firing that was totally even from top to bottom.
>
> For the most part this is not a problem because one of my glaze combos do=
es fine at cone 10/11 but the other one needs a full cone 11 or else it jus=
t looks bad. The latter glaze combo can not be fired at the top of the kiln=
for this reason - and since this glaze is a better seller I need to start =
firing entire loads of it.
>
> I have always considered this to be impossible but I just thought to ask =
if anyone out there has a similar kiln that really fires evenly - and if so=
could you email me some pictures of your bagwall/target brick setup?
>
>
>
> I currently have a very high bagwall, at least =BE of the way up. At the =
moment, if cone 11 is just barely touching at the top of the kiln it is dow=
n flat toward the bottom - and the glazes look a lot nicer there. On averag=
e, the space between the bagwall bricks is about 1" and I suspect that if I=
put them closer together I will get more heat toward the top (I have done =
this in the past) but then the glazes will not look as nice toward the bott=
om as they currently are.
>
>
>
> Anyone care to comment on this one? I have heard others on clayart say th=
ey have kilns that fire evenly but I have not seen pictures of the inside s=
o I don't really know what the trick is.
>
>
>
> Thanks!
>
> Paul
>
>
>
--
Sumi von Dassow
www.herwheel.com
sumi@herwheel.com
Paul Borian on fri 21 may 10
i have a downdraft gas/oil kiln that is about 70 cu.ft. with forced air =
=3D
burners. It is a car kiln with two burners that come in from the back. I =
=3D
have adjusted the bagwall numerous times (and at first I did not even =3D
use one) but have never had a firing that was totally even from top to =3D
bottom.
For the most part this is not a problem because one of my glaze combos =3D
does fine at cone 10/11 but the other one needs a full cone 11 or else =3D
it just looks bad. The latter glaze combo can not be fired at the top of =
=3D
the kiln for this reason - and since this glaze is a better seller I =3D
need to start firing entire loads of it.
I have always considered this to be impossible but I just thought to ask =
=3D
if anyone out there has a similar kiln that really fires evenly - and if =
=3D
so could you email me some pictures of your bagwall/target brick setup?
=3D20
I currently have a very high bagwall, at least =3DBE of the way up. At the =
=3D
moment, if cone 11 is just barely touching at the top of the kiln it is =3D
down flat toward the bottom - and the glazes look a lot nicer there. On =3D
average, the space between the bagwall bricks is about 1" and I suspect =3D
that if I put them closer together I will get more heat toward the top =3D
(I have done this in the past) but then the glazes will not look as nice =
=3D
toward the bottom as they currently are.
=3D20
Anyone care to comment on this one? I have heard others on clayart say =3D
they have kilns that fire evenly but I have not seen pictures of the =3D
inside so I don't really know what the trick is.
=3D20
Thanks!
Paul
jonathan byler on fri 21 may 10
it is pretty rare in my experience to get a downdraught kiln as you =3D20
describe to fire hotter at the bottom than the top. most have the =3D20
opposite problem. this might have something to do with the kiln being =3D2=
0=3D
much taller than it is wide, or it might have something to do with =3D20
your bagwall, or who knows? in ours if you start out too slow and =3D20
don't get the burners cranked up fast enough, the top gets to a nice =3D20
red heat before the bottom by quite a long shot. differences of =3D20
hundreds of degrees. I fixed that by turning up the air/gas faster =3D20
and having more turbulence in the kiln at the start of the firing.
changing how you stack your kiln (more dense top or bottom) seems to =3D20
affect things as well. if you are getting not enough heat at the top, =3D2=
0=3D
try stacking more loosely up there to allow the gasses to flow through =3D2=
0=3D
there more.
maybe post some pictures on flickr of the empty kiln, and some with it =3D2=
0=3D
stacked as you usually stack it?
-jon
On May 21, 2010, at 1:22 PM, Paul Borian wrote:
> i have a downdraft gas/oil kiln that is about 70 cu.ft. with forced =3D20=
=3D
> air burners. It is a car kiln with two burners that come in from the =3D2=
0=3D
> back. I have adjusted the bagwall numerous times (and at first I did =3D2=
0=3D
> not even use one) but have never had a firing that was totally even =3D20=
=3D
> from top to bottom.
>
> For the most part this is not a problem because one of my glaze =3D20
> combos does fine at cone 10/11 but the other one needs a full cone =3D20
> 11 or else it just looks bad. The latter glaze combo can not be =3D20
> fired at the top of the kiln for this reason - and since this glaze =3D20=
=3D
> is a better seller I need to start firing entire loads of it.
>
> I have always considered this to be impossible but I just thought to =3D2=
0=3D
> ask if anyone out there has a similar kiln that really fires evenly =3D20=
=3D
> - and if so could you email me some pictures of your bagwall/target =3D20=
=3D
> brick setup?
>
>
>
> I currently have a very high bagwall, at least =3DBE of the way up. At =
=3D20=3D
> the moment, if cone 11 is just barely touching at the top of the =3D20
> kiln it is down flat toward the bottom - and the glazes look a lot =3D20
> nicer there. On average, the space between the bagwall bricks is =3D20
> about 1" and I suspect that if I put them closer together I will get =3D2=
0=3D
> more heat toward the top (I have done this in the past) but then the =3D2=
0=3D
> glazes will not look as nice toward the bottom as they currently are.
>
>
>
> Anyone care to comment on this one? I have heard others on clayart =3D20
> say they have kilns that fire evenly but I have not seen pictures of =3D2=
0=3D
> the inside so I don't really know what the trick is.
>
>
>
> Thanks!
>
> Paul
Lee Love on fri 21 may 10
Paul,
Sounds like your kiln is firing pretty even. Put the
cooler glazes at the top and hotter glazes at the bottom
At Northern Clay Center, the kilns are configured the same
way. The three I fire are also hotter on the bottom (I get 11 on the
bottom and 10 on the top.) The bag walls aren't too high. They have
a slanting target brick (45* angle, low end toward the burner, high
end laying on another brick) right in the middle of the bag wall on
each side, half way down the back way, to deflect the flame upward.
--
Lee, a Mashiko potter in Minneapolis
http://mingeisota.blogspot.com/
=3D93Observe the wonders as they occur around you. Don't claim them. Feel
the artistry moving through and be silent.=3D94 --Rumi
steve graber on sat 22 may 10
my kiln is about=3DA0the same size - 70 cubic foot.=3DA0 it fires extremely=
eve=3D
n from top=3DA0down, front to back.=3DA0 no bag walls.=3DA0 up facing burne=
rs to =3D
an arched ceiling (elipse actually) with an exit flew at the back on the fl=
=3D
oor.=3DA0 there's a picture of it on my website.=3DA0 =3D0A=3D0Amy only sna=
g is a d=3D
oor that needs a better seal.=3DA0 =3D0A=3D0Aand i need potter friends to h=
elp me=3D
fill the thing up with more frequency than i can do on my own...=3DA0 =3D0=
A=3DA0=3D
Steve Graber, Graber's Pottery, Inc=3D0AClaremont, California USA=3D0AThe S=
teve=3D
Tool - for awesome texture on pots! =3D0Awww.graberspottery.com steve@grab=
er=3D
spottery.com =3D0A=3D0A=3D0AOn Laguna Clay's website=3D0Ahttp://www.lagunac=
lay.com/=3D
blogs/ =3D0A=3D0A=3D0A=3D0A----- Original Message ----=3D0A> From: Paul Bor=
ian DOCRET.COM>=3D0A> To: Clayart@LSV.CERAMICS.ORG=3D0A> Sent: Fri, May 21, 201=
0 11=3D
:22:57 AM=3D0A> Subject: Does your downdraft gas kiln fire evenly?=3D0A> =
=3D0A> i=3D
have a downdraft gas/oil kiln that is about 70 cu.ft. with forced air burn=
=3D
ers. =3D0A> It is a car kiln with two burners that come in from the back. I=
h=3D
ave adjusted =3D0A> the bagwall numerous times (and at first I did not even=
u=3D
se one) but have never =3D0A> had a firing that was totally even from top t=
o =3D
bottom.=3D0A=3D0AFor the most part =3D0A> this is not a problem because one=
of my=3D
glaze combos does fine at cone 10/11 but =3D0A> the other one needs a full=
c=3D
one 11 or else it just looks bad. The latter glaze =3D0A> combo can not be =
fi=3D
red at the top of the kiln for this reason - and since this =3D0A> glaze is=
a=3D
better seller I need to start firing entire loads of it.=3D0A=3D0AI =3D0A>=
have =3D
always considered this to be impossible but I just thought to ask if anyone=
=3D
=3D0A> out there has a similar kiln that really fires evenly - and if so c=
ou=3D
ld you =3D0A> email me some pictures of your bagwall/target brick setup?=3D=
0A=3D
=3D0A=3D0A=3D0AI =3D0A> currently have a very high bagwall, at least =3DBE =
of the way=3D
up. At the moment, if =3D0A> cone 11 is just barely touching at the top of=
t=3D
he kiln it is down flat toward =3D0A> the bottom - and the glazes look a lo=
t =3D
nicer there. On average, the space =3D0A> between the bagwall bricks is abo=
ut=3D
1" and I suspect that if I put them closer =3D0A> together I will get more=
h=3D
eat toward the top (I have done this in the past) but =3D0A> then the glaze=
s =3D
will not look as nice toward the bottom as they currently =3D0A> are.=3D0A=
=3D0A=3D
=3D0A=3D0AAnyone care to comment on this one? I have heard others on =3D0A>=
claya=3D
rt say they have kilns that fire evenly but I have not seen pictures of the=
=3D
=3D0A> inside so I don't really know what the trick is.=3D0A=3D0A=3D0A> =
=3D0A=3D0AThan=3D
ks!=3D0A=3D0APaul=3D0A=3D0A=3D0A
douglas fur on sat 22 may 10
Paul
My first thought is that the flame is "too big" for the kln but the bleed
holes in the bagwall put a wrinkle in that idea. So it's
- The kiln is over powered- the flame doesn't get going until it's half
way out the kiln (like the kid who brought the fire department down on
himself by putting 10-12 foot flames out the chimney. you could see them
over the rooftops blocks away.)
- Or the bleed holes short circuit the flames and the top is missed and
the bottom overfired
two theories with opposite solutions...
DRB
Burien
On Fri, May 21, 2010 at 11:22 AM, Paul Borian wrote:
> i have a downdraft gas/oil kiln that is about 70 cu.ft. with forced air
> burners. It is a car kiln with two burners that come in from the back. I
> have adjusted the bagwall numerous times (and at first I did not even use
> one) but have never had a firing that was totally even from top to bottom=
=3D
.
>
> For the most part this is not a problem because one of my glaze combos do=
=3D
es
> fine at cone 10/11 but the other one needs a full cone 11 or else it just
> looks bad. The latter glaze combo can not be fired at the top of the kiln
> for this reason - and since this glaze is a better seller I need to start
> firing entire loads of it.
>
> I have always considered this to be impossible but I just thought to ask =
=3D
if
> anyone out there has a similar kiln that really fires evenly - and if so
> could you email me some pictures of your bagwall/target brick setup?
>
>
>
> I currently have a very high bagwall, at least =3DBE of the way up. At th=
e
> moment, if cone 11 is just barely touching at the top of the kiln it is d=
=3D
own
> flat toward the bottom - and the glazes look a lot nicer there. On averag=
=3D
e,
> the space between the bagwall bricks is about 1" and I suspect that if I =
=3D
put
> them closer together I will get more heat toward the top (I have done thi=
=3D
s
> in the past) but then the glazes will not look as nice toward the bottom =
=3D
as
> they currently are.
>
>
>
> Anyone care to comment on this one? I have heard others on clayart say th=
=3D
ey
> have kilns that fire evenly but I have not seen pictures of the inside so=
=3D
I
> don't really know what the trick is.
>
>
>
> Thanks!
>
> Paul
>
Snail Scott on sun 23 may 10
On May 21, 2010, at 1:22 PM, Paul Borian wrote:
> i have a downdraft gas/oil kiln that is about 70 cu.ft. with forced
> air burners...one of my glaze combos does fine at cone 10/11 but the
> other one needs a full cone 11 or else it just looks bad. The latter
> glaze combo can not be fired at the top of the kiln for this reason...
I'd look to the damper adjustment, first.
-Snail
Craig Martell on sun 23 may 10
Hello Paul:
I have a very similar kiln as to space, burner configuration. It
fires very evenly but I don't use forced air and that may be adding
to the hot bottom in your kiln. Forced air burners can have a very
short, hot flame that really torches the bottom of the kiln. I don't
know if that's a big deal with your kiln but it's something to consider.
regards, Craig Martell Hopewell, Oregon
| |
|
