reduction firing - smokey peeps

updated thu 22 mar 07

Lesley Anton on mon 12 mar 07

Hi all,
Reduction firing question here.

I have an 8 year old Laguna Updraft 9 cf fiber gas kiln. I have had
it for about a year and am still learning the ins and outs but have
had quite a few successful reduction firings with it.
Currently, I am having a weird thing happen though. Usually, upon
bringing the gas up slowly to about 3" WC, I get ready to reduce at
about 1650 -1700 F. then close the damper to about 1 1/2", to get my
nice orange, pungent flame. The last 2 firings, there have been a
little flame peek out of the damper even before I shut it. Then when
I go to close the damper, I get my good smell, but then the flame is
a bit small, and there is a bit more smoke than normal. After
playing with the damper, shut not so much as before, I reduced for
about 1/2 hr, then opened it a bit till cone 9ish. During that long
acceleration period, there is way more smoke than normal. I opened
the damper more, then the temp went up way too fast - so I tried
closing the damper again a bit, even with the smoke, then turned the
gas down to 2 1/2", still smokey, then down to 2" - less smoke but
still more than I am comfortable with. The flame is the right size
(I think) and the right color (as per Les Haworth at Laguna and Linda
Arbuckle's entry) I made tiny adjustments )1/4" to 1" with the
damper. When I opened it back up to where it was for oxidation (3")
the smoke is still coming out. Argh! Eeking out of the peeps - both
top and bottom. How much smoke is normal? should I be expecting
some and I am freaking out needlessly? The load didn't seem to be
reduced enough is why I ask.

Upon reading tons of entries, I understand that the smoke is caused
by an imbalance - or a waste - too much reduction - but I am
wondering ,, because I have played around with the balance as much as
I can figure, maybe the smoke is caused by a carbon build up? or
something else? Gas pressure oddity? All the dials read normal.

Help!!



Lesley Anton
www.lesleyanton.com

Lesley Anton on tue 13 mar 07

Thanks for the quick responses,
Sorry, in my panic, I forgot to mention the damper/air situation.
The reason I am so confused is that normally, when kiln starts, I
have the damper set open at 3", then at 1650 F start reducing,
closing the damper to about 1 1/2" , then after 30 min, open back the
damper a bit to about 1 3/4" ......usually the duration of the firing
is a nice 6" orange flame with no smoke....the last 2 firings, no
matter how much I opened the damper back up, even to the starting
position at 3" there was smoke coming out of the top peep hole (when
it was shut), some off the top of the main damper flame and a little
even out of the thermocoupler hole, yikes!. I had never had to open
up that much before.

I understand the whole "wasted fuel," thing and that "the smoke is
not necessary for reduction effects"
I didn't want the smoke, believe me, I just was so freaked about
going out of reduction I was reluctant to continue opening. But I
guess since there was still an orange flame, and not blue/green I
could have kept opening the damper until the smoke stopped. Though,
when I did open it up more, the temp seemed to zoom up too fast.

Eric, I haven't heard about adjusting the burners during the firing.
The discs under my (6) burners are set around 1/2" - maybe they're
open too much? (I guess that wouldn't make sense) I do get a little
uneven reduction though, that might be why.

A friend of mine thought I might have gone up in temperature too
quickly, that might have caused some weird excess smoke/ heat issues
- I also had a very full load, which I don't always have. What is a
good length of time to go from 0 to reduction temp (1650 -1700F)? I
usually take about 5 hours. -is that too short? For all of you
experts out there, what is a typical total cone 10 reduction firing
time - 0 to cone 10?

Gosh, sorry about the 5 million questions in this email - but I just
joined this list and am chomping to know, know, know.

Thanks,
Lesley
www.lesleyanton.com



The
On Mar 13, 2007, at 8:26 AM, Erik Harmon wrote:

> Lesley Anton wrote:
> Upon reading tons of entries, I understand that the smoke is caused
> by an imbalance - or a waste - too much reduction - but I am
> wondering ,, because I have played around with the balance as much as
> I can figure, maybe the smoke is caused by a carbon build up? or
> something else? Gas pressure oddity? All the dials read normal.
>
>
> Lesley you dont say anything about altering your Air intake. Its
> been about ten years, but the Olympic I used to fire in college was
> the same size as yours and with the old burners we had I adjusted
> them at least 3 to 4 times a firing, in order to attain the right
> level of reduction and temp increase.
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> melpots@pclink.com.
>
>
>
>
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> ______________________________________________________________________
> ________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
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>
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> melpots@pclink.com.




Lesley Anton
Owner, designer, potter
Lesley Anton Handmade Ceramic Lighting
323.934.3463
lesleyanton@mac.com
www.lesleyanton.com

Chris Trabka on tue 13 mar 07

Lesley,

I once fired an updraft kiln like yours without an oxyprobe. My suggestion
is to, remove a peep and check the flame coming out of the peep. I
discovered a flame one to two inches long indicated good reduction. I never
had any smoke. The largest problem I had was seeing the flame when it was
bright outside. I cut the bottom and side out of a black 1 gallon plant pot
and used that as a background to see the flame. Little or no flame will
indicate that you are in oxidation, Too much flame (smoke) indicates that
you can either reduce the gas or open the damper.

As a side note, I live in Michigan, and the relative humidity has a
significant impact in my firings. On a sultry August afternoon, my gas is
at 2.5" WC. On a crisp October afternoon, my gas is at 3.5" WC.

Chris

>Hi all,
>Reduction firing question here.
>
>I have an 8 year old Laguna Updraft 9 cf fiber gas kiln. I have had
>it for about a year and am still learning the ins and outs but have
>had quite a few successful reduction firings with it.
>Currently, I am having a weird thing happen though. Usually, upon
>bringing the gas up slowly to about 3" WC, I get ready to reduce at
>about 1650 -1700 F. then close the damper to about 1 1/2", to get my
>nice orange, pungent flame. The last 2 firings, there have been a
>little flame peek out of the damper even before I shut it. Then when
>I go to close the damper, I get my good smell, but then the flame is
>a bit small, and there is a bit more smoke than normal. After
>playing with the damper, shut not so much as before, I reduced for
>about 1/2 hr, then opened it a bit till cone 9ish. During that long
>acceleration period, there is way more smoke than normal. I opened
>the damper more, then the temp went up way too fast - so I tried
>closing the damper again a bit, even with the smoke, then turned the
>gas down to 2 1/2", still smokey, then down to 2" - less smoke but
>still more than I am comfortable with. The flame is the right size
>(I think) and the right color (as per Les Haworth at Laguna and Linda
>Arbuckle's entry) I made tiny adjustments )1/4" to 1" with the
>damper. When I opened it back up to where it was for oxidation (3")
>the smoke is still coming out. Argh! Eeking out of the peeps - both
>top and bottom. How much smoke is normal? should I be expecting
>some and I am freaking out needlessly? The load didn't seem to be
>reduced enough is why I ask.
>
>Upon reading tons of entries, I understand that the smoke is caused
>by an imbalance - or a waste - too much reduction - but I am
>wondering ,, because I have played around with the balance as much as
>I can figure, maybe the smoke is caused by a carbon build up? or
>something else? Gas pressure oddity? All the dials read normal.
>
>Help!!
>
>
>
>Lesley Anton
>www.lesleyanton.com
>
>___________________________________________________________________________
___
>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 tue 13 mar 07

The smoke is not necessary for reduction effects.
It is unburned fuel/incomplete burned fuel and just a waste of fuel.
Some back pressure at spy holes will indicate reduction, but excess smoke &
carbon at peep holes is not needed.

How do you have the primary air controls (disks on back of burners) set?
Perhaps they are closed too much.

At school, with our downdraft Geil, I have the primary air controls set at
the width of two popsicle sticks. This gives a reduction in the 1800 degree
range simply by adjusting gas pressure.

At home, on my Olympic updraft, I have the air controls set a little more
open (1/4 - 3/8"), but I get uneven reduction, but I continue to work on
that.


--
William "Bill" Schran
wschran@cox.net
wschran@nvcc.edu
http://www.creativecreekartisans.com



On 3/12/07 6:54 PM, "Lesley Anton" wrote:

> Upon reading tons of entries, I understand that the smoke is caused
> by an imbalance - or a waste - too much reduction - but I am
> wondering ,, because I have played around with the balance as much as
> I can figure, maybe the smoke is caused by a carbon build up? or
> something else? Gas pressure oddity? All the dials read normal.

Erik Harmon on tue 13 mar 07

Lesley Anton wrote:
Upon reading tons of entries, I understand that the smoke is caused
by an imbalance - or a waste - too much reduction - but I am
wondering ,, because I have played around with the balance as much as
I can figure, maybe the smoke is caused by a carbon build up? or
something else? Gas pressure oddity? All the dials read normal.


Lesley you dont say anything about altering your Air intake. Its been about ten years, but the Olympic I used to fire in college was the same size as yours and with the old burners we had I adjusted them at least 3 to 4 times a firing, in order to attain the right level of reduction and temp increase.
______________________________________________________________________________
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.




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Pamela Regentin on thu 15 mar 07

Ivor,

I have an updraft with atmospheric burners. I've only fired once so far. I got good body reduction but so-so glaze reduction. I did close the discs on opposite corners (there are eight burners)during reduction. Without checking my notes I don't remember if it was two or four burners. Anyway, I wondered about the placement of the tops of the burners, the head you called it, which are placed just below the port hole so that there is really no way to control all that secondary air that is mixing with the fuel. Is it correct to have the burner heads just below the port hole and not up into the port hole? Would closing the discs be sufficient to control the air intake there? How many of the burners need to have those discs closed and should any remain open?

I obviously have a lot of experimenting yet to do but your post is the first I have seen that addressed the secondary air at the port holes.

Thanks,
Pam

Ivor and Olive Lewis wrote: Dear Lesley Anton,

You say <>

Those disks or shutters that allow air to mix with your gas before it passes into the kiln need to be closed to some degree prior to adjusting your damper to get back pressure. It is essential that some unburned fuel enters the chamber of a kiln otherwise there is nothing to react with ingredients in clays and glazes .

Another factor that is sometimes overlooked is air that is entrained due to a venturi effect caused by the passage of gas into a kiln and chimney draw . This is secondary air that moves between the burner head and the hole into the kiln chamber. It assists gas to burn on the outside of the flame envelope.

I set my own burners and check by inspecting the flame. I close the shutters until I can see a white tip at the end of the flame. If the flame is all blue then all of the fuel is being consumed so reduction will not happen even if you close the damper and see flame issue from open "peeps". Set with the white tips combustion is almost complete. When I wish to reduce I wind my burner shutters to reduce the air flow, get more white in the flame and then, with the "Peep" open, I close the damper until a small white tip flame issues. The I put the plug back in the "peep". I would close the shutter more but keep the damper setting the same for reducing Copper glazes.

Best regards and Good firings,

Ivor Lewis.
Redhill,
South Australia.

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Ivor and Olive Lewis on fri 16 mar 07

Dear Lesley Anton,=20

You say <The discs under my (6) burners are set around 1/2" - maybe they're open =
too much? (I guess that wouldn't make sense) I do get a little uneven =
reduction though, that might be why.>>

Those disks or shutters that allow air to mix with your gas before it =
passes into the kiln need to be closed to some degree prior to adjusting =
your damper to get back pressure. It is essential that some unburned =
fuel enters the chamber of a kiln otherwise there is nothing to react =
with ingredients in clays and glazes .=20

Another factor that is sometimes overlooked is air that is entrained due =
to a venturi effect caused by the passage of gas into a kiln and chimney =
draw . This is secondary air that moves between the burner head and the =
hole into the kiln chamber. It assists gas to burn on the outside of the =
flame envelope.

I set my own burners and check by inspecting the flame. I close the =
shutters until I can see a white tip at the end of the flame. If the =
flame is all blue then all of the fuel is being consumed so reduction =
will not happen even if you close the damper and see flame issue from =
open "peeps". Set with the white tips combustion is almost complete. =
When I wish to reduce I wind my burner shutters to reduce the air flow, =
get more white in the flame and then, with the "Peep" open, I close the =
damper until a small white tip flame issues. The I put the plug back in =
the "peep". I would close the shutter more but keep the damper setting =
the same for reducing Copper glazes.

Best regards and Good firings,

Ivor Lewis.
Redhill,
South Australia.