Ron Roy on sat 6 mar 04
Hi Lois,
Often what happens is the flame from the burners is fulled out of the kiln
by the flue because the burners are right next to the flue - so the flame
does not get to the top back - because the flame is shooting towards the
front.
Directing some of the flame up is the way to heat up that part of the kiln.
A target brick will help push more flame up.
The only way to solve the problem is to force the flame up more. Moving
your target brick closer will help that - I don't know how close it will
have to be - you will just have to try. How close is it now?
The target brick will flare the flame out so that it hits the kiln wall by
the way - and the bricks will suffer - you may want to use some refractory
to protect those bricks - a shelf or kiln wash for instance.
You may find the bottom front will start getting cooler because - as you
move the target brick closer to the burner - some heat will be diverted
form the bottom front - have cones in all areas till you get this worked
out - preferably set in a darker clay - that way you will see if there is
reduction as well as measuring heat work.
All those horizontal burners suffer from the same problem - they heat in an
uneven way. Firing slower and soaking will help a lot but getting more heat
to the top back will do the most good.
RR
> HI Ron,
> Thanks for your help.
> Just unloaded a firing with my new digital pyrometer,... I have been
> consistently getting under fired pots even when cone 10 was flat sometimes
> with 11 flat the inside of bowls were still under fired. So I got a
> fluke 52!
>
>
> With the digital my back top was consistently 30degrees cooler than the
>front top . Bottom front to back was even.
>
> I fired to 10 medium bend. Then tried the firing down everyone is talking
> about....I cooled to 1850 then relit and fired for 2 hours between 1900 and
> 2000 degrees.
>
> Everything was GREAT except the top back two shelves.
>
> It is a downdraft 40 cuft burners in the back next to flue. Natural gas
>power
> burners. I have no bag wall, but do have a one target brick 16 inches
>from
> the burners.
>
> I moved it 1 inch closer to the burners for this firing,
> My questions is would moving the target brick closer to burners help
>deflect
> to top back?
> How close is to close? Any other ideas?
>
> By the way the glaze you redid for me "opal" is great! (when I don't
> under-fire it!)
>
> Thanks again for your help
> Lois
>
> --
> Lois Sharpe
>
>
>
>>
>> On 3/4/04 10:29 AM, "Ron Roy" wrote:
>>
>>> Hi Lois,
>>>
>>> The best advice I ever got was to direct flame to where you want it hotter.
>>>
>>> For instance - if the back is hotter and that is where the flue exit is -
>>> create a tunnel so more of the flame is drawn to the front before getting
>>> into the flue - best would be an adjustable flue then can be opened
>>> anywhere to draw more flame towards that area.
>>>
>>> Target bricks can also be used to direct flame.
>>>
>>> If I had some idea about where the cooler spots were perhaps I could be
>>> more specific.
>>>
>>> Soaking at the end of a firing does help as does how the shelves are
>>>stacked.
>>>
>>> RR
>>>
>>>
>>>
>>>> I fire a 40 cu foot downdraft gas kiln. Cone 10 reduction. I am having
>>>> problems getting the front to back even, top and bottom no problem.
>>>> What are the best things to try? (I know one at a time!)
>>>> Any ideas appreciated.
>>>> Thanks
>>>> Lois
>>>>
>>>> --
>>>> Lois Sharpe
>>>>
>>>>
>>>
>>> Ron Roy
>>> RR#4
>>> 15084 Little Lake Road
>>> Brighton, Ontario
>>> Canada
>>> K0K 1H0
>>> Phone: 613-475-9544
>>> Fax: 613-475-3513
>>>
>>>
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>------ End of Forwarded Message
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
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