kiln questions - front loading

I am looking at buying a kiln, primarily for heat treating, but know that I
want to do some fusing and slumping later on.
I am looking at the Paragon HT14D which can be upgraded to 2300F (M2 steel
use). It has the 12 key controller and is front loading. This question is
really whether the elements on the side and not the top will greatly affect
the outcome if I do glass work in it.
It is somewhat reasonably priced and spacious for what I what to do -
13x13x8.

Any help would be appreciated.

--
Steve Worcester
www.turningwood.com
Better Woodturning through Technology
(And a hell of alotta practice)

Steve,
I have 2 kilns.
One front loading 48" H x 25" wide x 35" back.
The other top loading 27" high x 51" wide x 39" back.
Both have only side elements, but we use them mainly for bending and
slumping (convex glass only, not plates, bowls etc.) from 1130F to 1330F,
although they will go to 1650F and 2100F respectively.
I notice that besides the normal cooler spots near the floor and top, the
middle front and back in the big kiln is cooler, with heat concentrated in
the corners.
It is most likely that a smaller kiln like you are considering (especially
in the height) would see less problem with this, but for fusing etc, I would
consider that top elements would be most beneficial for even heat.
Maybe it doesn't matter, it will be interesting to see what fusers think.
Best regards,
Les
www.tudorglass.com.au

"Steve Worcester" wrote in message
...
I am looking at buying a kiln, primarily for heat treating, but know that
I
want to do some fusing and slumping later on.
I am looking at the Paragon HT14D which can be upgraded to 2300F (M2 steel
use). It has the 12 key controller and is front loading. This question is
really whether the elements on the side and not the top will greatly
affect
the outcome if I do glass work in it.
It is somewhat reasonably priced and spacious for what I what to do -
13x13x8.

Any help would be appreciated.

--
Steve Worcester
www.turningwood.com
Better Woodturning through Technology
(And a hell of alotta practice)

On 6/2/04 6:03 PM, in article , "Steve
Worcester" wrote:

I am looking at buying a kiln, primarily for heat treating, but know that I
want to do some fusing and slumping later on.
I am looking at the Paragon HT14D which can be upgraded to 2300F (M2 steel
use). It has the 12 key controller and is front loading. This question is
really whether the elements on the side and not the top will greatly affect
the outcome if I do glass work in it.
It is somewhat reasonably priced and spacious for what I what to do -
13x13x8.

Any help would be appreciated.

I have the Paragon TnF-J-14-1 which is the same size cavity with ceramic
fiber lining and elements on sides and back (12-key, max temp 1700F). I
bought it through Bullseye, a prominent glass manufacturer--they use it in
their shop and classes. In their fusing tables, they recommend initial
ramping of a side firing kiln to be 1.5 times more slow than a top firing
kiln. I've tried it with good results. I agree with the other poster that
the small size of the cavity means uneven heating is less of an issue. If I
were to get a larger front loader from Paragon, I'd get the GL18 or GL24
with top, front, side and back elements.

I'm not sure what the lining is in the kiln you're looking at, but if it is
firebrick meant for ceramics, it may not cool fast enough and cause
devitrification. Bullseye states that their glass is less prone to devit,
but I've had some pieces do it even when using their recommended schedules.

Cheers,
Dianne

"Di-a-rama" wrote in message
m.com...
On 6/2/04 6:03 PM, in article , "Steve
Worcester" wrote:

I am looking at buying a kiln, primarily for heat treating, but know
that I
want to do some fusing and slumping later on.
I am looking at the Paragon HT14D which can be upgraded to 2300F (M2
steel
use). It has the 12 key controller and is front loading. This question
is
really whether the elements on the side and not the top will greatly
affect
the outcome if I do glass work in it.
It is somewhat reasonably priced and spacious for what I what to do -
13x13x8.

Any help would be appreciated.

I have the Paragon TnF-J-14-1 which is the same size cavity with ceramic
fiber lining and elements on sides and back (12-key, max temp 1700F). I
bought it through Bullseye, a prominent glass manufacturer--they use it in
their shop and classes. In their fusing tables, they recommend initial
ramping of a side firing kiln to be 1.5 times more slow than a top firing
kiln. I've tried it with good results. I agree with the other poster
that
the small size of the cavity means uneven heating is less of an issue. If
I
were to get a larger front loader from Paragon, I'd get the GL18 or GL24
with top, front, side and back elements.

I'm not sure what the lining is in the kiln you're looking at, but if it
is
firebrick meant for ceramics, it may not cool fast enough and cause
devitrification. Bullseye states that their glass is less prone to devit,
but I've had some pieces do it even when using their recommended
schedules.

Cheers,
Dianne

After reading Diannes post, I should correct a possible misunderstanding.
My kilns have elements all round the 4 sides.

Interesting, Diannes comment re slower cooling and devit.
I have never had that problem with slow cooling.
I just programme them for night cooking, and let them cool naturally after a
run.
Maybe it is a problem from higher casting / fusing temps ?
Has only ever been very minor with tin bloom, but I don't think there is
very much that can be done to prevent this.
I have fire bricks in both kilns, one a very heavy dense brick, the other
much lighter.
If I ever build / have one built myself, I way just use FC board and
blanket.

Regards,
Les

"Steve Worcester" wrote in message
...
I am looking at buying a kiln, primarily for heat treating, but know that
I
want to do some fusing and slumping later on.
I am looking at the Paragon HT14D which can be upgraded to 2300F (M2 steel
use). It has the 12 key controller and is front loading. This question is
really whether the elements on the side and not the top will greatly
affect
the outcome if I do glass work in it.
It is somewhat reasonably priced and spacious for what I what to do -
13x13x8.

I've read the contributions of Dianne and Les to this question and found
them helpful -thought I would add my perspective.

I am on my third kiln now. I started with a front loader (18" x 18" x 18")
which was heated on three sides (i.e. no elements on the door). It was a
pottery kiln and I bought it because it was cheap and it was available (not
being a big second hand kiln market where I live). For fusing and slumping,
I found two major problems. The first was a significant temperature
diferential top to bottom and front to back. According to my pyrometer, the
top of the kiln was 30 - 50 degrees hotter than the bottom and the edge of
the shelf near the door was 15 degrees cooler than at the back. I saw these
temerature variations replicated in fused pieces.
The second problem was caused by crash cooling (as one is advised to do) -
that is to quickly reduce the temperature below the devitrification
temperature. With a front loading kiln this means opening the door which
allows hot air to escape from the top and cold air to come in from beneath.
I found this sudden temperature change often cracked ceramic molds I was
using for slumping. Notwithstanding these problems, the kiln was a reliable
old workhorse which was generally fine for casting, pot melts and working
with float glass.

I am currently using two top loading kilns - one has side elements as well
as elements in the ceramic brick lid and the other side elements and a fibre
lid. I find the top elements give a very even temperature across the whole
shelf - the major problem is the occasional tiny fragment of brick which
falls out and inevitably lands in the middle of the most prized piece.

Hope this helps

Gordon
www.divineglass.com.au

On 6/3/04 6:48 PM, in article
, "figjam"
wrote:

Interesting, Diannes comment re slower cooling and devit.
I have never had that problem with slow cooling.
I just programme them for night cooking, and let them cool naturally after a
run.
Maybe it is a problem from higher casting / fusing temps ?

Yes--it happens when I do the full fuse program with a soak at 1500F
(Bullseye recommended). There has been some minor devit with two of their
newer colors--cranberry and coral cathedrals. With a ceramic fiber kiln,
crash cooling is not really necessary (I've tried it both ways), so I may
use devit spray if I continue to use those colors. I'm still learning, but
there's no teacher like experience.

Cheers,
Dianne

Thanks everyone for your help. I am guessing I am in for an interesting but
exciting learning curve.

--
Steve Worcester
www.turningwood.com
Better Woodturning through Technology
(And a hell of alotta practice)



"Gordon Williamson" wrote in message
...

"Steve Worcester" wrote in message
...
I am looking at buying a kiln, primarily for heat treating, but know
that
I
want to do some fusing and slumping later on.
I am looking at the Paragon HT14D which can be upgraded to 2300F (M2
steel
use). It has the 12 key controller and is front loading. This question
is
really whether the elements on the side and not the top will greatly
affect
the outcome if I do glass work in it.
It is somewhat reasonably priced and spacious for what I what to do -
13x13x8.

I've read the contributions of Dianne and Les to this question and found
them helpful -thought I would add my perspective.

I am on my third kiln now. I started with a front loader (18" x 18" x
18")
which was heated on three sides (i.e. no elements on the door). It was a
pottery kiln and I bought it because it was cheap and it was available
(not
being a big second hand kiln market where I live). For fusing and
slumping,
I found two major problems. The first was a significant temperature
diferential top to bottom and front to back. According to my pyrometer,
the
top of the kiln was 30 - 50 degrees hotter than the bottom and the edge of
the shelf near the door was 15 degrees cooler than at the back. I saw
these
temerature variations replicated in fused pieces.
The second problem was caused by crash cooling (as one is advised to do) -
that is to quickly reduce the temperature below the devitrification
temperature. With a front loading kiln this means opening the door which
allows hot air to escape from the top and cold air to come in from
beneath.
I found this sudden temperature change often cracked ceramic molds I was
using for slumping. Notwithstanding these problems, the kiln was a
reliable
old workhorse which was generally fine for casting, pot melts and working
with float glass.

I am currently using two top loading kilns - one has side elements as well
as elements in the ceramic brick lid and the other side elements and a
fibre
lid. I find the top elements give a very even temperature across the
whole
shelf - the major problem is the occasional tiny fragment of brick which
falls out and inevitably lands in the middle of the most prized piece.

Hope this helps

Gordon
www.divineglass.com.au

The big problem with a front loader when slumping or fusing is you can
not see what's going on in the rear of the piece. My first kiln was a
front loader and I had to turn pieces around to see if I got a full
slump. Top loader is better for this kind of work.

On 5 Jun 2004 08:47:26 -0700, (vic) wrote:

The big problem with a front loader when slumping or fusing is you can
not see what's going on in the rear of the piece. My first kiln was a
front loader and I had to turn pieces around to see if I got a full
slump. Top loader is better for this kind of work.


Wrong

I slump a stack of 8 shelves at one time in my frond loading kiln ,
and all come out perfect

cheers

Jason

"vic" wrote in message
m...
The big problem with a front loader when slumping or fusing is you can
not see what's going on in the rear of the piece. My first kiln was a
front loader and I had to turn pieces around to see if I got a full
slump. Top loader is better for this kind of work.
==================================================

What about the blast of superheated air when you lift the lid for a peek? I
guess you don't peek...... so why not drill a peephole in the back of your
front-loader? It seems to simple and obvious a solution, so I reckon you had
a reason not to. I love my front loading, ancient Paragon GL-22 .... though
heating isn't perfectly even, I have yet to see any kiln that is. The newer
GL-22 with elements in the sides and front would seem ideal IMHO.

Full truth requires that I disclose that my favorite kiln of all is my
home-built 29x59" bell kiln .... I lift the top 'box' with a brake-winch and
can hold it open 2-3 inches this way and lose almost NO heat in the process,
while allowing viewing or glass manipulation from ALL sides. Now THAT's a
goooood design .... going to use it for metal enameling shortly. I've even
used it to cure powdercoating.

Such useful devices.... I once used the Paragon to melt the cheese on an
omelet.... but that's another story....hahahahahah.

Regards, Jacques Bordeleau