Mmpottery on thu 22 jan 98
I just fired my 40 cu.ft. kiln for the second time. The first firing went to
temperature fine.^6. Although during the first firing I drilled the orifices
out from3/16 to 5/16 around body reduction. Natural Gas. This time I could not
get to temperature to save my life. I am wondering about a few things and
wondered if any body could help me.
First of all the bagwall- I have it 4 bricks high. Should it be solid or
spaced? If there are spaces in it does it matter where they are? I had spaces
in the bagwall and I am wondering if the flame was shooting through the space
and out the stack.Downdraft kiln by the way. Should there be a target brick
so the flame hits that and goes up?
Second- My bottom shelves were totally (hardly any space) filling the space.
They are set one brick high off the floor. Could they have been blocking the
flame pattern also?
Third- The orifice size. It is at the maximum ( I think). Could there have
been too much gas going in? And if there had been wouldnt it have been
reducing? The burners are typical venturi types. very simple burners. Natural
draft. I have plenty of gas pressure I think. It's like 1/2 lb. Double normal
house pressure.
When I was firing I tried everything I knew. Reducing, Oxidizing, turning the
gas down, turning the gas up, shutting the primary off, shutting the secondary
off, full on with both etc etc.
The bottom back got way hot ^10 and the bottom front was ^5 barely, the top
was somewhere around ^2. It was a once fire so I started it Friday night.
Fired it till Sunday. Nuts I know. It was very windy Saturday so I thought it
might have something to do with it going so slow. But then the wind died down
and it still wouldnt budge from where I finally turned it off. The firing
from Hell.
Does anyone have any suggestions??????? I really would appreciate any help!!
Michelle in Colorado freaking out!@#$%^&*
Jennifer Boyer on fri 23 jan 98
Hi Michelle,
Raise that bagwall. Make it higher in the back and taper it down a little
towards the front to draw the flame forward. Close up any spaces you have
in the bricks in at least the 2 first courses....probably the first 3
towards the back. My kiln is 45 inches high in the side walls and I have an
18 high bag wall. No spaces in the first 11.5 inches, then very small
spaces- 1 inch wide or so, spaced about 6 inches apart. I use soaps(half
bricks) above the first 2 courses of regular sized brick so i have alot of
flexibility on where the spaces are and how many there are based on where I
want the heat to go. Bag walls are an art form....and i bet every kiln
needs a different set up. Keep alot of cones in your kiln so you know where
the heat is going. It's telling you a story.
Take Care
Jennifer
>----------------------------Original message----------------------------
>I just fired my 40 cu.ft. kiln for the second time. The first firing went to
>temperature fine.^6. Although during the first firing I drilled the orifices
>out from3/16 to 5/16 around body reduction. Natural Gas. This time I could not
>get to temperature to save my life. I am wondering about a few things and
>wondered if any body could help me.
>
>First of all the bagwall- I have it 4 bricks high. Should it be solid or
>spaced? If there are spaces in it does it matter where they are? I had spaces
>in the bagwall and I am wondering if the flame was shooting through the space
>and out the stack.Downdraft kiln by the way. Should there be a target brick
>so the flame hits that and goes up?
>
>Second- My bottom shelves were totally (hardly any space) filling the space.
>They are set one brick high off the floor. Could they have been blocking the
>flame pattern also?
>
>Third- The orifice size. It is at the maximum ( I think). Could there have
>been too much gas going in? And if there had been wouldnt it have been
>reducing? The burners are typical venturi types. very simple burners. Natural
>draft. I have plenty of gas pressure I think. It's like 1/2 lb. Double normal
>house pressure.
>
>When I was firing I tried everything I knew. Reducing, Oxidizing, turning the
>gas down, turning the gas up, shutting the primary off, shutting the secondary
>off, full on with both etc etc.
>
>The bottom back got way hot ^10 and the bottom front was ^5 barely, the top
>was somewhere around ^2. It was a once fire so I started it Friday night.
>Fired it till Sunday. Nuts I know. It was very windy Saturday so I thought it
>might have something to do with it going so slow. But then the wind died down
>and it still wouldnt budge from where I finally turned it off. The firing
>from Hell.
>
>Does anyone have any suggestions??????? I really would appreciate any help!!
>
>Michelle in Colorado freaking out!@#$%^&*
~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*
Jennifer Boyer
Thistle Hill Pottery
Montpelier, Vt. 05602
jboyer@plainfield.bypass.com
Tracy Dotson on sat 24 jan 98
Michelle...I started too E--mail you some answers on your kiln and how to get
some control with it's fireing but found that each question needed too much
explanation to help you make changes. I have been building and helping
people for the past too many years and would like to help you. My wife and I
are production potters near Penland NC. My phone # is 704-765-8222 I have
also found that AOL has a free instant message service where if two people
are in AOL and on line they can send messages and ask questions back and
forth. If this isn't convient for you we can always do the e-mail thing.
Hoping to hear from you at thepottery@aol.com or the phone
Good luck Tracy Dotson
Ray Carlton on sun 25 jan 98
At 16:10 23/01/98 EST, you wrote:
>----------------------------Original message----------------------------
>Hi Michelle,
sounds like drilling out the orifices has made the kiln out of tune go back
to the original size orifice ...why did you drill them out iuf the first
firing wes ok ???the bagwall placement will only eeven out your firing it
should not really have an effect on getting to temp [at a given spot in the
kiln]
cheers :)
Ray Carlton
Michelle McCurdy on mon 26 jan 98
Hi Jennifer,
Thanks for responding to my kiln problem! I thought I would do just
that. Close up the bagwall and maybe make it taller.Problem is to do alot at
first ,or one step at a time? I will figure it out. I'll let you know what
happens. Where are you? What kinds of pots do you make?? Michelle
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