Roger Korn on tue 7 jan 03
Catherine,
Was the fiber blanket fiberglass or ceramic fiber? If it was fiberglass,
there's a good chance that the upper surface of the lid was hot enough
to melt the fiberglass. The reason this didn't happen with the other
kiln would be that the other kiln's lid was better insulated itself,
thus placing the surface temperature at a lower point on the gradient
from 2280 F to room temp.
Just wild speculation,
Roger
Catherine White wrote:
>...
> I placed a double layer of fiber blanket, 2' X 2', atop the lid just as I do with my smaller 18" ID Paragon kiln...
>
--
Roger Korn
McKay Creek Ceramics
In AZ: PO Box 463
4215 Culpepper Ranch Rd
Rimrock, AZ 86335
928-567-5699
In OR: PO Box 436
31330 NW Pacific Ave.
North Plains, OR 97133
503-647-5464 <-for a while
Catherine White on tue 7 jan 03
I did a first-time, dry-run/empty firing of my old Crusader kiln to =
see if it would heat to around 2300 degrees. There were some strange =
happenings.
I placed a double layer of fiber blanket, 2' X 2', atop the lid =
just as I do with my smaller 18" ID Paragon kiln.
The happenings were that, though the temp never exceeded 2280f, the =
little kiln god setting on the fiber blanket had his foot glaze all =
crazed for about a quarter of an inch up. The bottoms were blackened and =
the footprints were semi-melted in the blanket. Never happened before in =
years of cone 10 firing. Also, the kiln was slightly rocking while hot. =
It returned to a stable setting when cooled. The kiln's fire color was =
the standard orange-red that indicates it's getting up there.=20
The kiln is an ancient Crusader- a round kiln with inner dimensions =
of 24" dia and 30" depth, setting on the typical four sided frame. We =
placed a 16 gauge steel disc between the bottom of the kiln and the =
frame on which it sets to better support the kiln's bottom.=20
The kiln has 6 infinite switches that control 12 elements. During =
this firing, I saw that one set of elements wasn't working. I used my =
new pyrometer to check the temp rise. It has a ceramic protector. I used =
it a couple days earlier in a bisque fire in the Crusader and it matched =
the cones exactly. There is no kiln sitter at present.
Here are the pyrometer readings:
1PM All set to low.
3PM All set to medium........... 725 f
4PM All set to high ............... 1435 f
6PM ................................... 1990 f
8 PM ..................................... 2165 f
9PM ...................................... 2230 f
10PM ...................................... 2260 f
11PM ...................................... 2280 f
I turned it off at this point since it obviously will fire to ^10 =
when the bad set of elements are replaced. We're installing a Dawson =
Ramp Controller and this firing was to ascertain that the kiln worked.=20
Both kilns are outside so there's no fire danger, but why would the =
top heat to the point of the fiber blanket slightly glowing on top. =
Never did that with the 18" ID Paragon.=20
Any input is appreciated! =20
Catherine in Yuma, AZ
Two ancient electric kilns. Both outside.
=20
Catherine White on wed 8 jan 03
No, that's not the answer. When I fire in the smaller Paragon and lift a
corner of the fiber blanket, it's all aglow in there. Awesome. But the heat
doesn't get through the top layer.
Where is Rimrock, AZ? If you're anywhere near Yuma, you'll have to come
visit us.
Thanks.........
Catherine in Yuma, AZ
Two ancient electric kilns. Both outside.
----- Original Message -----
> Was the fiber blanket fiberglass or ceramic fiber? If it was fiberglass,
> there's a good chance that the upper surface of the lid was hot enough
> to melt the fiberglass. The reason this didn't happen with the other
> kiln would be that the other kiln's lid was better insulated itself,
> thus placing the surface temperature at a lower point on the gradient
> from 2280 F to room temp.
> Roger
>
> Catherine White wrote:
>
> I placed a double layer of fiber blanket, 2' X 2', atop the lid just as I
do with my smaller 18" ID Paragon kiln...
> Roger Korn
william schran on wed 8 jan 03
Catherine asked: ...... why would the top heat to the point of
the fiber blanket slightly glowing on top? She had put a layer or 2
of fiber blanket on top of a Crusader kiln lid.
I had tried this idea a few years ago with a L&L kiln, 29" diameter.
Lid is only 2.5" thick so I figured adding layer of fiber blanket
could only help hold the heat in. Worked fine for bisque and cone 6
firings, but at cone 10 I smelled something burning, lifted the edge
of the fiber and found the IFB glowing red under it. After the kiln
cooled and I removed the fiber I found the lid had cracked. I now use
this kiln only for bisque firing.
Bill
Arnolds Home Improvements on thu 9 jan 03
William
It say's in the manual that came with my L&L that it was OK to put a couple
of layers of fiber on the lid. I haven't tried it yey because I was afraid
It would crack. Now I guess we know it will
Gene Arnold
mudduck@advi.net
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