Beth Collier-Fogdall on wed 3 jan 07
Hello,
I am a high school art teacher who has been firing this Alpine HF-20 updraft
gas kiln for the last 2.5 years. It is quiet old, and was just re-bricked
now it looks great, but.... it is firing very hot on top, worse then before
they re-bricked it. Any ideas on how to get some balance back into the
tempatures betweent the bottom and the top? It was off before the
re-bricking, but not like this!
Thanks,
Beth
Victoria E. Hamilton on wed 3 jan 07
Beth -
I fire this kiln weekly. Yup - rebricked several years ago and now fires
hotter on top than the bottom unless heroic measures are taken.
I'd be glad to speak with you. You can reach me at 206.779.9483. I am in
Seattle, WA.
Vicki Hamilton
Millennia Antica Pottery
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Beth
Collier-Fogdall
Sent: Wednesday, January 03, 2007 6:53 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: [CLAYART] Updraft gas kiln, Alpine HF-20
Hello,
I am a high school art teacher who has been firing this Alpine HF-20 updraft
gas kiln for the last 2.5 years. It is quiet old, and was just re-bricked
now it looks great, but.... it is firing very hot on top, worse then before
they re-bricked it. Any ideas on how to get some balance back into the
tempatures betweent the bottom and the top? It was off before the
re-bricking, but not like this!
Thanks,
Beth
____________________________________________________________________________
__
Send postings to clayart@lsv.ceramics.org
You may look at the archives for the list or change your subscription
settings from http://www.ceramics.org/clayart/
Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.
Mike Gordon on wed 3 jan 07
Beth,
Start keeping a written record of temp, time, and gas and damper
changes and then you can get a better picture of what to change first.
What cone are you firing too? Mike Gordon
On Jan 3, 2007, at 6:53 AM, Beth Collier-Fogdall wrote:
> Hello,
> I am a high school art teacher who has been firing this Alpine HF-20
> updraft
> gas kiln for the last 2.5 years. It is quiet old, and was just
> re-bricked
> now it looks great, but.... it is firing very hot on top, worse then
> before
> they re-bricked it. Any ideas on how to get some balance back into the
> tempatures betweent the bottom and the top? It was off before the
> re-bricking, but not like this!
> Thanks,
> Beth
>
> _______________________________________________________________________
> _______
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
>
William & Susan Schran User on wed 3 jan 07
On 1/3/07 9:53 AM, "Beth Collier-Fogdall" wrote:
> I am a high school art teacher who has been firing this Alpine HF-20 updraft
> gas kiln for the last 2.5 years. It is quiet old, and was just re-bricked
> now it looks great, but.... it is firing very hot on top, worse then before
> they re-bricked it. Any ideas on how to get some balance back into the
> tempatures betweent the bottom and the top?
I'm currently firing a Geil downdraft at school, but fire a small Olympic
updraft in my own studio. I don't know that all that I do to achieve even
firings will work for you, but it may help. Both of these kilns have natural
draft burners, and if the Alpine also uses natural draft burners, then some
of these ideas might work.
First, you may need to simply slow down the firing - a longer firing can
often help even things out.
Set the primary air controls on the burners and leave them at that setting
all the time. On both of the kilns I fire, I have the disk set at an opening
the width of two popsicle sticks (flat side). I never change this setting.
Gas pressure - don't go too high. Geil recommends 7wci (natural gas) of
pressure as the highest setting. I never go above 3.5 wci and get to ^10 in
8-10 hours. At home I don't have a gas gauge. I fire with propane and would
guess by the sound that I never get higher than one pound of pressure, most
likely less. I change by sound,
Damper - make very minor changes. The Geil's damper is set at 2 3/4 opening
and stays there until near the end of the firing when it is opened to 3.
These numbers are inches. At home I have made pencil marks on the lid of the
kiln on either side of the flue opening. I use 2 IFB to be the damper. I
start 1 1/4 inches in from the edge of the flue, then close in to 3/4 - 1
inch opened at the end.
I've also found for both kilns that I can get a more even firing easier by
loading taller pots (more open) at the bottom and shorter work (more shelves
closer together) at the top. For the updraft at home, I also position a
small shelf (6" square) about 1 1/2 - 2 inches right below the flue opening
inside the kiln - this backs up the pressure in the kiln a bit.
Hope this helps, Bill
--
William "Bill" Schran
wschran@cox.net
wschran@nvcc.edu
http://www.creativecreekartisans.com
| |
|
