Fred Paget on mon 14 sep 98
By the way, my new higher intermediate pressure natural gas is in service
now and I have 28 inches of pressure at the meter. With the kiln on full
force the pressure through that 110 feet of 3/4 inch line shows 20 inches
at the kiln.
I fired Saturday and got it up to cone 11 in about 7 hours and never had
to use more than 15 inches on the gauges.
That is too fast and I will have to go down in orifice size a little or
something as I now have too many BTU from the two power burners.It is hard
to control the rise between 250 degrees and 1000 degrees it wants to go up
so fast.
The glaze was Vegas copper red on porcelain bisque and I got some
beauties from the middle shelf which was cone 9. The bottom shelf was
overfired to cone 11. The top shelf was underfired as cone 8 did not go
down but was just starting to curve at the top.
The bottom shelf pots were clear celadon like and runny. Does anybody
know if overfiring copper red will produce a clear very light blue or is it
due to not going into reduction at the bottom?
Also can I refire those underfired pots or are they for the hammer? They
are red all right but matte and a sort of bad pinky red color.
I have an oxygen probe and also a type R thermocouple in the kiln. The
oxyprobe is in the middle of the flattop roof as per instructions and the
thermocouple is in the middle of the door. I had cone packs on each shelf.
The 2 power burners fire in horizontally from the rear on each side at
the bottom and the flue is between them. The bottom shelf is above the flue
on hard bricks at the side so the flue opening is actually at the front of
the kiln. A layout similar to the Bailey kiln.
The kiln is a 15 cubic feet MFT type flat top down draft with a 12 foot
chimney, and the stacking space is a bit higher than a cube.
There are two target bricks at the front of the kiln in front of the
power burners tilted at 45 degrees. I am wondering if I should move them to
the rear more to try to get more heat to the top. Also would it be a good
idea to make a sort of bag wall by filling in the sides of the lower two
shelves with bricks? The bottom shelf already has this.
Fred Paget
From Fred Paget, in marvelous Marin County, California, USA
Alex, Aurora and Leah Solla on wed 16 sep 98
About your not-copper reds.... essentially they did not reduce before
1800F. What you did was melt the glaze before reducing it. Once there is
glass being melted, it is remarkably hard to reduce the copper. Sorry. You
can try refiring to just past dull red heat and then striking. It wont give
the same red at all, but it can be interesting. If you really want true
reds... then these are destined for the hammer. Good luck
Alex in utah.
At 07:37 PM 9/14/98 -0400, you wrote:
>----------------------------Original message----------------------------
> By the way, my new higher intermediate pressure natural gas is in service
>now and I have 28 inches of pressure at the meter. With the kiln on full
>force the pressure through that 110 feet of 3/4 inch line shows 20 inches
>at the kiln.
> I fired Saturday and got it up to cone 11 in about 7 hours and never had
>to use more than 15 inches on the gauges.
> That is too fast and I will have to go down in orifice size a little or
>something as I now have too many BTU from the two power burners.It is hard
>to control the rise between 250 degrees and 1000 degrees it wants to go up
>so fast.
> The glaze was Vegas copper red on porcelain bisque and I got some
>beauties from the middle shelf which was cone 9. The bottom shelf was
>overfired to cone 11. The top shelf was underfired as cone 8 did not go
>down but was just starting to curve at the top.
> The bottom shelf pots were clear celadon like and runny. Does anybody
>know if overfiring copper red will produce a clear very light blue or is it
>due to not going into reduction at the bottom?
> Also can I refire those underfired pots or are they for the hammer? They
>are red all right but matte and a sort of bad pinky red color.
> I have an oxygen probe and also a type R thermocouple in the kiln. The
>oxyprobe is in the middle of the flattop roof as per instructions and the
>thermocouple is in the middle of the door. I had cone packs on each shelf.
> The 2 power burners fire in horizontally from the rear on each side at
>the bottom and the flue is between them. The bottom shelf is above the flue
>on hard bricks at the side so the flue opening is actually at the front of
>the kiln. A layout similar to the Bailey kiln.
> The kiln is a 15 cubic feet MFT type flat top down draft with a 12 foot
>chimney, and the stacking space is a bit higher than a cube.
> There are two target bricks at the front of the kiln in front of the
>power burners tilted at 45 degrees. I am wondering if I should move them to
>the rear more to try to get more heat to the top. Also would it be a good
>idea to make a sort of bag wall by filling in the sides of the lower two
>shelves with bricks? The bottom shelf already has this.
>Fred Paget
>
>
> From Fred Paget, in marvelous Marin County, California, USA
>
Grimmer on wed 16 sep 98
Fred,
I can think of two things you can try right off the bat.
There should be two post-and-lintel structures in your kiln, between the
target bricks and the bottom shelf on each side. Move the posts closer
together (slightly) to decrease heat on the bottom and heat up the top.
These are pretty sensitive adjustments in my MFT, so do a little and see
what happens. Let me know if that's not clear.
The other thing is to push your damper in a bit more and cut the primary
air at the burners a bit to get better reduction at the bottom. Both these
things will tend to push heat down in a reducing kiln, too, so it's a
balancing act between that and the bricks inside. Remember to make one
adjustment at a time when you fire ands see what happens. Take notes and be
patient. When you get your MFT figured out, it will be a champ!
The copper red I use mostly just runs off the pot if over fired. It
stays red. You could certainly refire the under-fired ones. See what
happens.
steve grimmer
marion illinois.
----------
>From: Fred Paget
>To: CLAYART@LSV.UKY.EDU
>Subject: Re: Gas line size for kiln.
>Date: Mon, Sep 14, 1998, 6:37 PM
>
>----------------------------Original message----------------------------
> By the way, my new higher intermediate pressure natural gas is in service
>now and I have 28 inches of pressure at the meter. With the kiln on full
>force the pressure through that 110 feet of 3/4 inch line shows 20 inches
>at the kiln.
> I fired Saturday and got it up to cone 11 in about 7 hours and never had
>to use more than 15 inches on the gauges.
> That is too fast and I will have to go down in orifice size a little or
>something as I now have too many BTU from the two power burners.It is hard
>to control the rise between 250 degrees and 1000 degrees it wants to go up
>so fast.
> The glaze was Vegas copper red on porcelain bisque and I got some
>beauties from the middle shelf which was cone 9. The bottom shelf was
>overfired to cone 11. The top shelf was underfired as cone 8 did not go
>down but was just starting to curve at the top.
> The bottom shelf pots were clear celadon like and runny. Does anybody
>know if overfiring copper red will produce a clear very light blue or is it
>due to not going into reduction at the bottom?
> Also can I refire those underfired pots or are they for the hammer? They
>are red all right but matte and a sort of bad pinky red color.
> I have an oxygen probe and also a type R thermocouple in the kiln. The
>oxyprobe is in the middle of the flattop roof as per instructions and the
>thermocouple is in the middle of the door. I had cone packs on each shelf.
> The 2 power burners fire in horizontally from the rear on each side at
>the bottom and the flue is between them. The bottom shelf is above the flue
>on hard bricks at the side so the flue opening is actually at the front of
>the kiln. A layout similar to the Bailey kiln.
> The kiln is a 15 cubic feet MFT type flat top down draft with a 12 foot
>chimney, and the stacking space is a bit higher than a cube.
> There are two target bricks at the front of the kiln in front of the
>power burners tilted at 45 degrees. I am wondering if I should move them to
>the rear more to try to get more heat to the top. Also would it be a good
>idea to make a sort of bag wall by filling in the sides of the lower two
>shelves with bricks? The bottom shelf already has this.
>Fred Paget
>
>
> From Fred Paget, in marvelous Marin County, California, USA
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