Dave Lyons on mon 28 sep 09
Gene, I'd like to know why you wanted (or needed) to switch from a flat top
kiln to an arch.
Dave Lyons
-----Original Message-----
From: Clayart [mailto:Clayart@LSV.CERAMICS.ORG] On Behalf Of mudduck
Sent: Monday, September 28, 2009 7:25 PM
To: Clayart@LSV.CERAMICS.ORG
Subject: fiber on the roof
I've taken the flat top off my kiln and will be replacing it tomorrow with
an arch. The arch will be one brick thick (3 or 4 inches I didn't measure).
Several kilns I've looked at have two layers of a fiber blanket on top of
them. Some have what looks like a cement castable mixture of some sort. Are
either of these necessary?? If so which is better?? Or is something else
better??
Thanks!!!
Gene
mudduck@mudduckpottery.net
www.mudduckpottery.net
David Hendley on mon 28 sep 09
Gene, if you build a kiln with 9" thick walls and arch bricks
for the roof, the roof is not insulated as much as the walls.
So, extra insulation on the roof is not 'necessary', but it makes
sense to bring it up to the same insulation value as the walls.
As for what is better, or best, I've always gone for economy.
Insulation is insulation.
When I had some extra Kaowool I rolled it out over the arch.
For my current kiln, I had a bunch of broken but still good
IFBs (most were only broken in half). I simply laid them out
over the arch and then filled in and top-coated them with
fireclay mortar. It has worked well going for on 10 years.
My kiln takes more than 48 hours to cool to opening
temperature.
David Hendley
david@farmpots.com
http://www.farmpots.com
----- Original Message -----
I've taken the flat top off my kiln and will be replacing it tomorrow with
an arch. The arch will be one brick thick (3 or 4 inches I didn't measure).
Several kilns I've looked at have two layers of a fiber blanket on top of
them. Some have what looks like a cement castable mixture of some sort. Are
either of these necessary?? If so which is better?? Or is something else
better??
gary navarre on mon 28 sep 09
Well Gene,=3D0A=3D0A My arch (catenary) kiln wall is 4=3DBD" hard high heat=
duty =3D
firebrick, 1" fiber blanket (that stuff Tim Fredricks can get you), and 2=
=3D
=3DBD" scrap IFB. The pignose, Bourry Firebox, and stack are 9" of hard bri=
ck=3D
. My first prototype of this design only had 2=3DBD" firebrick (set on edge=
),=3D
1" blanket and IFB. That inch of blanket is what made all the difference i=
=3D
n getting to temperature. Tim thought I might be putting a castable/slop ov=
=3D
er the blanket and said to cover it with a sheet of plastic first, just to =
=3D
keep the slop from sticking to the blanket before it had solidified, but I =
=3D
thought it might smell if it tried to burn off so I left it off... even tho=
=3D
ugh I did use a sloppy lag to set the IFB scraps in place. I don't know abo=
=3D
ut coverage with castable but a 50lb. bag of dry mix costs about $45 bucks,=
=3D
and a 2'x25' roll of blanket is usually about a hundred bucks. I mixed the=
=3D
castable 50/50 with lag (50/50 fireclay and EPK + 10% fine grog or kyanite=
=3D
/mulite) and
used it to make special shapes and level or fill spaces between bricks in =
=3D
the curve instead of cutting the hard brick to fit. I didn't use much on th=
=3D
e IFB in the event I need to take it apart but... as I think about it I mig=
=3D
ht have used the castable/lag mix to glue a couple square feet of IFB toget=
=3D
her at a time so I could lift them off in manageable sections, like the she=
=3D
ll of a turtle. Oh well, what's done is done, I better get to finishing the=
=3D
load before it freezes out there and now we have 40=3DB0. I never shoulda =
br=3D
agged about being able to fire in the winter. Good luck and stay in there e=
=3D
h!=3D0AGary Navarre=3D0ANavarre Pottery=3D0ANavarre Enterprises=3D0ANorway,=
Michiga=3D
n, USA=3D0Ahttp://www.youtube.com/GindaUP=3D0Ahttp://public.fotki.com/Ginda=
UP/=3D
=3D0A=3D0A=3D0A--- On Mon, 9/28/09, mudduck wr=
ote:=3D
=3D0A=3D0A> From: mudduck =3D0A> Subject: [Clay=
art] f=3D
iber on the roof=3D0A> To: Clayart@LSV.CERAMICS.ORG=3D0A> Date: Monday, Sep=
temb=3D
er 28, 2009, 7:25 PM=3D0A> I've taken the flat top off my kiln=3D0A> and wi=
ll b=3D
e replacing it tomorrow with an arch. The arch=3D0A> will be one brick thic=
k =3D
(3 or 4 inches I didn't measure).=3D0A> Several kilns I've looked at have t=
wo=3D
layers of a fiber=3D0A> blanket on top of them. Some have what looks like =
a =3D
cement=3D0A> castable mixture of some sort. Are either of these=3D0A> neces=
sary=3D
?? If so which is better?? Or is something else=3D0A> better??=3D0A> =3D0A>=
Thank=3D
s!!!=3D0A> Gene=3D0A> mudduck@mudduckpottery.net=3D0A> www.mudduckpottery.n=
et=3D0A>=3D
=3D0A=3D0A=3D0A
mudduck on mon 28 sep 09
I've taken the flat top off my kiln and will be replacing it tomorrow =3D
with an arch. The arch will be one brick thick (3 or 4 inches I didn't =3D
measure). Several kilns I've looked at have two layers of a fiber =3D
blanket on top of them. Some have what looks like a cement castable =3D
mixture of some sort. Are either of these necessary?? If so which is =3D
better?? Or is something else better??
Thanks!!!
Gene
mudduck@mudduckpottery.net
www.mudduckpottery.net
Steve Irvine on mon 28 sep 09
Hi Gene,
My kiln has two inches of Fiberfax blanket on the roof, and it works
very well to insulate the kiln. The arch is made of G26 insulation fire
brick.
http://www.steveirvine.com/kiln.html
This outdoor kiln, even in the middle of winter, takes at least 36
hours to cool down from cone 10. The Fiberfax is very easy to put into
place, and remove and reuse if necessary. When this kiln was originally
built I had a layer of castable on top of the blanket, but when I
rebuilt the arch ten years ago I didn't bother with the castable and it
works just fine.
Hope this helps.
Steve
http://www.steveirvine.com
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