Clay on tue 27 mar 12
Hello one and all,
After hours of studying the Kiln books intending to but my own, I then
ended up buying a second-hand kit-kiln, simply because it was the
cheaper option. The only down side of this, is that you don't get to
decide design, you're stuck with what's given you, simply trusting the
previous owner that it fires well.
Well, it fires awful. For my needs anyway let's say.
All the heat sits up at the top of the kiln and leaves the bottom
shelves about a cone to a cone and a half underfired.
For background ... I once-fire earthenware to 03, and preferably, I'd
like to fire tall pieces the full height of chamber.
I'm now at the point of simply pulling it apart and using the bricks to
build from scratch using 'text-book' dimensions, but before I do...
thought I'd pass it by this forum and see if there are any more
experienced thoughts.
Details below, but my main though here is, how far is it worth squeezing
something to 'force' it to work .. as opposed to just building something
'right' in the first place ?
If I do rebuild, I'd be looking at a strict cube, with a burner either
side of the stacking area.
Many thanks in advance for any constructive comments !
Simon
Inner dimensions: 27.5" Wide; 23" deep; 33.5" high.
4.5" ifb inner wall, 4.5" Heavy outer wall. Roof arch 9" thick ifb with
fibre laid ontop.
On the width, on 1 side only, 2 burners (2*3" dia inlets =3D 14in^2 ) fire
vertically upwards through the floor.
Bagwall is a =BE" kiln shelf, have tried one 5" high, tried one 18" high.
Flue is 6&1/2 * 3 hole (19in^2 ) in kiln wall opposite burners at floor
level.
Flue leads to external box mortared together with clay/sand mix 3ft high
and then onto a 5" dia (19in^2 ) chimney liner.
Thoughts:
> It's too tall for it's width? 5" taller, which in itself doesn't seem
lot, but works out at 20%, which appears a lot!
> Burners on 1 side only ... not optimal design for even heat distribution=
?
> Burners fire vertically upward ... starving the lower areas of heat x
time ?
> Dry & roughly mortared chimney box leaking?
Steps tried so far:
> 5" bag and 18" bag wall
> Moving 'floor' kiln shelf against the bag and more gap on the flue side
> Moving 'floor' kiln shelf against the flue side wall, and more gaps on
the bag side.
> No chimney above kiln top, 6' of chimney above kiln top.
Liz Gowen 1 on tue 27 mar 12
Simon, I am guessing your name since you didn't sign your message, =3D
Before
going into a lot about the kiln If you can I suggest you resubmit this
question after next Tuesday April 3rd. Many of our very knowledgeable =3D
kiln
folks are going to a national pottery conference this week and won't be
reading clayart much if at all. I would also suggest you put up a blog, =3D
easy
to do , take some pictures inside out of the kiln If you are only =3D
getting
between 1to 1 1/2 cones off it sounds more like your firing needs =3D
tweaking.
How many times have you fired it, Is this your 1st reduction kiln, what =3D
have
you fired before. Do you intend to do low or high fire here. What is =3D
your
firing schedule like i.e. how fast do you take it up, do you reduce, and =
=3D
if
so do you do so with the damper and how much do you adjust. Sometimes =3D
you
have to slow a firing down to let the top and bottom even out. Type of
burners?. I bought a commercially available kiln with a very good =3D
reputation
but you can't just turn it on like the stove and expect it to fire. I am
still learning but getting better. My kiln is also a down draft, flue =3D
exits
at the bottom, My burners come in from the bottom and fire up. I do not =3D
have
a bag wall. Had similar issues with an updraft kiln several years ago =3D
with
the top too hot. This sounds fixable don't rip it apart just yet. =3D
Resubmit
next week when much of the list will be back....Liz Gowen
-----Original Message-----
From: Clayart [mailto:Clayart@LSV.CERAMICS.ORG] On Behalf Of Clay
Sent: Tuesday, March 27, 2012 5:17 AM
To: Clayart@LSV.CERAMICS.ORG
Subject: Kiln Design / re-design.
Hello one and all,
After hours of studying the Kiln books intending to but my own, I then =3D
ended
up buying a second-hand kit-kiln, simply because it was the cheaper =3D
option.
The only down side of this, is that you don't get to decide design, =3D
you're
stuck with what's given you, simply trusting the previous owner that it
fires well.
Well, it fires awful. For my needs anyway let's say.
All the heat sits up at the top of the kiln and leaves the bottom =3D
shelves
about a cone to a cone and a half underfired.
For background ... I once-fire earthenware to 03, and preferably, I'd =3D
like
to fire tall pieces the full height of chamber.
I'm now at the point of simply pulling it apart and using the bricks to
build from scratch using 'text-book' dimensions, but before I do...
thought I'd pass it by this forum and see if there are any more =3D
experienced
thoughts.
Details below, but my main though here is, how far is it worth squeezing
something to 'force' it to work .. as opposed to just building something
'right' in the first place ?
If I do rebuild, I'd be looking at a strict cube, with a burner either =3D
side
of the stacking area.
Many thanks in advance for any constructive comments !
Simon
Inner dimensions: 27.5" Wide; 23" deep; 33.5" high.
4.5" ifb inner wall, 4.5" Heavy outer wall. Roof arch 9" thick ifb with
fibre laid ontop.
On the width, on 1 side only, 2 burners (2*3" dia inlets =3D3D 14in^2 ) =3D
fire
vertically upwards through the floor.
Bagwall is a =3DBE" kiln shelf, have tried one 5" high, tried one 18" =3D
high.
Flue is 6&1/2 * 3 hole (19in^2 ) in kiln wall opposite burners at floor
level.
Flue leads to external box mortared together with clay/sand mix 3ft high =
=3D
and
then onto a 5" dia (19in^2 ) chimney liner.
Thoughts:
> It's too tall for it's width? 5" taller, which in itself doesn't seem
lot, but works out at 20%, which appears a lot!
> Burners on 1 side only ... not optimal design for even heat =3D
distribution
?
> Burners fire vertically upward ... starving the lower areas of heat x
time ?
> Dry & roughly mortared chimney box leaking?
Steps tried so far:
> 5" bag and 18" bag wall
> Moving 'floor' kiln shelf against the bag and more gap on the flue=3D20
> side Moving 'floor' kiln shelf against the flue side wall, and more=3D20
> gaps on
the bag side.
> No chimney above kiln top, 6' of chimney above kiln top.
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