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Bill Kielb reacted to Hulk in anyone know how to achieve this effect?
Perhaps Per B Sundberg, per image search
Per B Sundberg | Objekt med hål (2013), Available for Sale | Artsy | Ceramic art, Pottery sculpture, Sculpture art (pinterest.com)
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Bill Kielb got a reaction from neilestrick in Connecting gas kiln to house natural gas supply
Gas combustion made simple! At about 10:1 air / fuel you will get a nice blue efficient flame (natural gas, propane not so much), plenty of oxygen for efficient combustion. A nice blue base of the flame is a reasonable indication of an oxidizing fairly efficient flame so the answer to your question is basically yes it’s a decent indication enough primary air is coming in. . Venturi burners are sort of self calibrated within a pressure range of operation so the more gas pressure, the more primary air is sucked in by the Venturi effect. Your burners do not appear to have a primary air shutter and that is ok really. A nice blue color, devoid of yellow indicates you are operating within a reasonable efficient pressure range for this burner.
About 50%:of the air for combustion comes from the primary air and 50% secondary air. The secondary air enters around the burner or the hole in the bottom of the kiln where the burner penetrates.
when closing the damper there will be an absolute best position for a given gas pressure where you are losing the least amount of heat but still allowing enough secondary airflow through the kiln for all the gas to be burned efficiently. Close it more and flame efficiency drops, less secondary air comes in the holes around the burners.
Folks often set their gas pressure - then find the point where performance begins to drop and open their dampers slightly more from there to get near that perfect balance. Every increase in pressure generally requires a slight opening of the damper so patience is key until you learn about where the damper needs to be for a given pressure for your kiln.
Your stuff seems to be working as designed, I would’ suggest testing with a damper first, it seems you are close ……. before making changes to the original design. Meaningful fine tuning damper adjustments start about 1000 degrees btw.
There always seems to be a lot of confusion with combustion
Simple Bunsen burner pic below we use to teach primary and secondary air and a fuel air chart showing efficient mixtures you might find helpful.
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Bill Kielb got a reaction from Hulk in Connecting gas kiln to house natural gas supply
Gas combustion made simple! At about 10:1 air / fuel you will get a nice blue efficient flame (natural gas, propane not so much), plenty of oxygen for efficient combustion. A nice blue base of the flame is a reasonable indication of an oxidizing fairly efficient flame so the answer to your question is basically yes it’s a decent indication enough primary air is coming in. . Venturi burners are sort of self calibrated within a pressure range of operation so the more gas pressure, the more primary air is sucked in by the Venturi effect. Your burners do not appear to have a primary air shutter and that is ok really. A nice blue color, devoid of yellow indicates you are operating within a reasonable efficient pressure range for this burner.
About 50%:of the air for combustion comes from the primary air and 50% secondary air. The secondary air enters around the burner or the hole in the bottom of the kiln where the burner penetrates.
when closing the damper there will be an absolute best position for a given gas pressure where you are losing the least amount of heat but still allowing enough secondary airflow through the kiln for all the gas to be burned efficiently. Close it more and flame efficiency drops, less secondary air comes in the holes around the burners.
Folks often set their gas pressure - then find the point where performance begins to drop and open their dampers slightly more from there to get near that perfect balance. Every increase in pressure generally requires a slight opening of the damper so patience is key until you learn about where the damper needs to be for a given pressure for your kiln.
Your stuff seems to be working as designed, I would’ suggest testing with a damper first, it seems you are close ……. before making changes to the original design. Meaningful fine tuning damper adjustments start about 1000 degrees btw.
There always seems to be a lot of confusion with combustion
Simple Bunsen burner pic below we use to teach primary and secondary air and a fuel air chart showing efficient mixtures you might find helpful.
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Bill Kielb got a reaction from Rae Reich in Connecting gas kiln to house natural gas supply
Gas combustion made simple! At about 10:1 air / fuel you will get a nice blue efficient flame (natural gas, propane not so much), plenty of oxygen for efficient combustion. A nice blue base of the flame is a reasonable indication of an oxidizing fairly efficient flame so the answer to your question is basically yes it’s a decent indication enough primary air is coming in. . Venturi burners are sort of self calibrated within a pressure range of operation so the more gas pressure, the more primary air is sucked in by the Venturi effect. Your burners do not appear to have a primary air shutter and that is ok really. A nice blue color, devoid of yellow indicates you are operating within a reasonable efficient pressure range for this burner.
About 50%:of the air for combustion comes from the primary air and 50% secondary air. The secondary air enters around the burner or the hole in the bottom of the kiln where the burner penetrates.
when closing the damper there will be an absolute best position for a given gas pressure where you are losing the least amount of heat but still allowing enough secondary airflow through the kiln for all the gas to be burned efficiently. Close it more and flame efficiency drops, less secondary air comes in the holes around the burners.
Folks often set their gas pressure - then find the point where performance begins to drop and open their dampers slightly more from there to get near that perfect balance. Every increase in pressure generally requires a slight opening of the damper so patience is key until you learn about where the damper needs to be for a given pressure for your kiln.
Your stuff seems to be working as designed, I would’ suggest testing with a damper first, it seems you are close ……. before making changes to the original design. Meaningful fine tuning damper adjustments start about 1000 degrees btw.
There always seems to be a lot of confusion with combustion
Simple Bunsen burner pic below we use to teach primary and secondary air and a fuel air chart showing efficient mixtures you might find helpful.
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Bill Kielb got a reaction from Russ in Connecting gas kiln to house natural gas supply
Just under 3% less inspired ! But to your excellent point, when estimating burner output elevation needs to be corrected for as well as the heat content of your natural gas supplied. Both can combine to be very significant in mid and high altitude burner deigns. While as a percentage O2 is still just under 21% more space exists between air molecules so quite a different mixture and burner settings sort of like quite a bit different O2 absorbed with every breath! Your body can adjust or acclimate much more so than your burners. Good catch! This is definitely an important part of understanding what you have and designing for what you will need.
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Bill Kielb reacted to Rae Reich in Connecting gas kiln to house natural gas supply
Hard to imagine a flue-plus-damper situation for that kiln. Think you’ll find that even minuscule adjustments of a damper will make a difference. Patience required in your observations and note taking. Not sure about your Venturi design, but mine do have a threaded section at the bottom to adjust primary air. Again, minor adjustments and patient observation. Try just the damper first.
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Bill Kielb got a reaction from Rae Reich in Connecting gas kiln to house natural gas supply
Might want to just fire with a damper initially to see what this needs. Lots of updrafts just fire into a hood without a direct connect flue for simplicity.
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Bill Kielb got a reaction from moogie in firing without glazing in an electric kiln
Just realized, harder to do with LED Christmas lights these days!
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Bill Kielb reacted to Russ in Connecting gas kiln to house natural gas supply
This. One thing Ive found with fuel burning kilns not reaching temp is not enough oxygen. It seems like youve found the correct amount of gas by adjusting pressure up and down. .. but at 5000ft plus above sea level we have way less oxygen per cubic ft than at sea level.
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Bill Kielb reacted to Ang in Cone Art Kiln 1822D will not work after elements change
Guys! You're all out here saving lives! For the life of me I don't know how I read this chart so wrong, I swear I have the worst case of pregnancy brain.
I hope this post one day helps someone as clueless as I was!
Thanks a million!!
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Bill Kielb reacted to Marilyn T in Can you predict the approximate drop/hold temperature in a drop and hold firing from the chemistry of a glaze?
Thanks Min and Bill.
I'll work on your suggestions over the next week and report back.
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Bill Kielb got a reaction from Marilyn T in Can you predict the approximate drop/hold temperature in a drop and hold firing from the chemistry of a glaze?
I am thinking this is bisque to 04 not 4. One thing strikes me in the recipe, boron is fairly high for cone 6. About 0.15 ought to get you cone 6, so this likely begins to melt much earlier. Might be worth an experiment or two reducing the Fritt a bit. Saves on an expensive ingredient and ought to reduce fluidity a bit which might be ideal. Definitely need to test to see if it affects the glaze positively or negatively.
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Bill Kielb got a reaction from Hulk in firing without glazing in an electric kiln
Just realized, harder to do with LED Christmas lights these days!
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Bill Kielb reacted to neilestrick in Interesting Cooling Cycle Info
I usually fire my kilns at night so I don't really see what's happening with actual temps in the kiln, but today I started it up in the morning and was in the studio in the evening and got to see exactly what was happening during the cooling cycle. I do a slightly-slow cooling cycle to even out the results in my 3 kilns because they all cool at drastically different rates due to their sizes. I do a drop from the peak down to 2000F, then cool at 175F/hr down to 1500F. This gives me identical results from all 3 of my kilns. This firing I'm talking about here is in my 10 cubic foot L&L EQ2827-3, which has 3 zones, and was packed very tight in the middle. I was surprised at just how much slower the middle cools compared to the top and bottom. This photo shows how it's going part way through the initial drop from peak temp to 2000F:
As you can see, the middle and the top are nowhere close to each other. In a normal firing segment, a 73 degree difference would stop the firing with an error code. So why isn't it doing that here? It's because the cooling rate is set at 9999, or full speed. Any time you use 9999, whether it's climbing or dropping, the controller lets the kiln do its thing and doesn't care if the sections aren't even. Firing up or down at 9999 is the fastest, but you sacrifice evenness. As the temp continues to drop, we see this:
Here you can see that the top section (TC1) has started firing again. The set point for this segment was 2000F, at which point it should start cooling at 175F/hr, yet the top section passed that by about 20 degrees before the relay kicked on and the controller stopped the drop. Why did it let it get so far below the set point? Because it's averaging the 3 zones. Once the average of the 3 zones hits the set point it will start to fire each section again as needed to match the set point.
I get a lot of questions from customers about error codes and cooling cycles. The biggest problem is that the kiln can't always keep up with the programmed cooling rate. There are a number of firing schedules out there on the internet that people are trying that use a rate of 600F/hr or more for the fast drop portion of the cooling cycle, and many kilns simply cannot cool that fast, especially the middle section. When you have a specific rate programmed, the controller will send out an error code if the kiln can't keep up with that rate. So if you want a really fast drop you should use 9999F/hr, not a specific rate. For most people doing slow cooling with cone 6 work it won't matter if the sections are not totally even during the drop. If you do need more precision, like if you're firing crystalline work and it's important that you don't overshoot any target temps, then you'll want to put in a slower drop rate that the kiln can actually keep up with, and the controller will keep the sections even and not overshoot set points.
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Bill Kielb reacted to neilestrick in Total Kiln Fail
That's a cone 05, not 5. That would explain why the cone 5 glazes didn't melt.
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Bill Kielb got a reaction from Hulk in Total Kiln Fail
So what turned the kiln off? Did the safety countdown timer turn it off too soon or did the cone melt in the sitter? If the sitter, then check it was not cone 05 instead of 5 (likely), sitter calibration ( that’s a lot of mis calibration, confirm everything else first before drastically recalibrating). You made it to red heat, that’s 1000f + so no stove oven would ever get near there. If all the above is not helpful, then testing the elements is likely next.
The good news, it made it to red heat and something shut it off. First task, what shut it off?
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Bill Kielb got a reaction from PeterH in Total Kiln Fail
So what turned the kiln off? Did the safety countdown timer turn it off too soon or did the cone melt in the sitter? If the sitter, then check it was not cone 05 instead of 5 (likely), sitter calibration ( that’s a lot of mis calibration, confirm everything else first before drastically recalibrating). You made it to red heat, that’s 1000f + so no stove oven would ever get near there. If all the above is not helpful, then testing the elements is likely next.
The good news, it made it to red heat and something shut it off. First task, what shut it off?
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Bill Kielb got a reaction from Hulk in Amaco Palladium glaze
I can second the cone 5 experience it did not like to go to cone 6 for me without pinholes with our clay. Also needed to apply it fairly thick, else it was just sort of some ugly. Just a reminder: it is NOT listed for food surfaces when we tried it. Took lots of firing tests to get one family bragging rights trophy fairly pinhole free. Also as it aged it became more black chrome than bright chrome.
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Bill Kielb got a reaction from Hulk in Help using kiln
The good news those appear to be silicon carbide elements which tend to have decent life ……. But the somewhat bad news is they have very different resistance readings as they heat up. Hopefully I am wrong and it’s just the picture and they are standard coiled kiln elements. If silicon carbide: my best thought, It may be necessary to run this kiln up to temperature and measure the hot resistance by actually measuring the amperage the kiln is drawing at top temperature. And if it makes top temperature then you will already know it is still serviceable or what temperature it can make. Place cones in this firing for sure and a pyrometer would be very useful.
If you are or have someone technically familiar with kilns and electric, it may be easiest to safely temporarily wire this kiln and fully supervise the firing. At peak temperature the amperage would be measured and wattage can be compared with the nameplate as well as hot resistance of the elements will be able to be derived from the amperage measured.
Sorry - I am at a loss for an easier method here, unfortunately silicon carbide resistance can change significantly when heated as well as aging. Maybe someone here has an easier way, this is the only definitive way I am aware of. Hopefully I am wrong and they are really traditional elements which means measure the resistance cold.
The Nova 1 manual seems to match your kiln shape and indicates 1/2 of the element with the fiber is a part number, so my thought would be when worn the entire fiber and element group would be replaced and installed 1/2 section at a time.
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Bill Kielb reacted to Hulk in Help using kiln
Ah, NOVA kiln
Here's a manual for what might be similar kilns novaman1.pdf (aakilns.com.au) ...which have lid vents!
Hence, the lid vent may be orginal.
The same company has a manual for NOVA controller novaman2.pdf (aakilns.com.au)
From this archived thread My weird kiln won't reach temp - Studio Operations and Making Work - Ceramic Arts Daily Community :
*begin quote*
Duncan bought rights to the Nova kiln during the 1970s. All the Duncan kiln manuals can be downloaded from the Paragon website. (We list the Duncan manuals because we contracted with Duncan to sell their kiln parts after they discontinued kiln production in 1997.) Here is the link to the manual for the Duncan EA-092 The Crafter-Plus and the EA-122 The Artist-Plus ceramic fiber kilns. I believe these models were originally Nova kilns
http://www.paragonweb.com/ManualInfo.cfm?CID=171
Sincerely,
Arnold Howard
Paragon Industries, L.P.
*end quote*
I'm not finding a direct match.
The EA092 does look similar ...but it isn't 240v and is much smaller.
LX855_Duncan_EA-092_EA-122_Manual.pdf (nxedge.io)
Try contacting Paragon?
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Bill Kielb reacted to Burnt Earth in Down Draft kiln questions
Thank you so much. This is exactly the information I was looking for in terms of firing this kiln.
the 60 orifices were just what comes in the burners I used. I was planning on drilling these as need be once I actually had some run time on this kiln. I do have a Testo stack analyzer that I can see exactly what is happening with my combustion so I can tune this unit very precisely. Once my valve train is built I will be able to dial the burners any where between 4” WC up to 10 Psi. I am trying to make it as automated as possible with at least 3 different firing rates done through some different controllers I have. I will be installing a ProFire 2100 BMS with flame ionization detection as my safety shutoff and with this I get some different control options and communications so we can monitor remotely.
The exhaust is currently 6x6” 3/8 thick square tubing. The kiln walls are approximately 6” thick soft finer fire brick and the exterior is lined with about 1/2” thick refractory blanket covered in a galvanized tin.
So we will run oxidizing flame till around 1500f and then go to a reduction firing after that. That’s really good info. Do you know what PPM of CO you would expect to see at reduction. Probably would need to be under 250PPM to prevent sooting.
What material are you guys using for dampers in a brick chimney and how are you installing them. Any pictures of that would be handy. For testing I was just going to slide a plate over the top of my exhaust.
I am not the potter (that’s my wife) so any pottery terms kind of blow right over my head. I am just taking care of the fire end of things so any help is greatly appreciated. My background is natural draft tube fired heaters up to 20mm btu/h and forced draft boilers up to around 50mm btu/h in oilfield and industrial applications. I have worked on hearth and fore hearth burners in fibreglass production but never anything to do with pottery kilns. I do have a large assortment of tools at my disposal so I’m sure I can get this kiln dialled right in for her.
once again thank you for all the help. It’s very much appreciated.
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Bill Kielb got a reaction from Rae Reich in Down Draft kiln questions
Really good to have the combustion background, definitely half the battle. Now some stuff that may help with your background and hopefully allows you to work through the design and tuning. In the end It’s pretty simple basic combustion stuff
The split between primary air and secondary air is about 50% Knowing that will allow you to figure reasonable over cuts around the burners where secondary air will enter, if not 1– 2 inch clearance is fine. Too small is generally the mistake. An ideal ratio air / fuel will be approximately 10:1 (oxidation) Reduction will be a dirty flame, producing lots of carbon monoxide and ……… pressurizing the kiln so very little air is drawn into the kiln through the over cuts. Reduction is achieved by closing the damper and and pressurizing the kiln from top to bottom. Very slight adjustments will establish this. Slightly pressurizing the kiln (very slight) will be enough to keep secondary air from coming in the over cuts which drives the kiln into reduction. (Very dirty flame - no soot needed, too rich and decreases reduction) Never go into early reduction below the PEL of the gas 1500 f or better. #60 is pretty small as most propane kilns are regulated down to inches, but at .#60 (for now) you likely will operate this in the 1-2 psi range, here is one of my favorite orifice tables https://www.gordonpiatt.com/wp-content/uploads/2021/07/Propane-Orifice-Chart-7.E.80.6-Rev-3-05.01.pdf easy to figure just what pressure you will need after you figure how much Btuh you need as well. Total guess, start at prox. 300,000 btuh, work your way down as practical.The kiln will be easier to fire and adjust in firing using low pressure. Inches of wc pressure Design your flue by table p41 here can help or 4” - 5” is likely reasonable and allow you to tune the height in the end. https://www.selkirkcorp.com/literature/Chimney_Venting_Sizing_Handbook.pdf Higher increases draw but also makes damper adjustments more sensitive. For an updraft kiln placing the thermocouple as near the kiln as practical in the flue likely give a decent reading of the average temps. Gas kilns are fired supervised by cone so watching when cones bend will be more important than peak temperature. Firing rates 500-600 f degrees per hour are generally considered fast for clay, but once in reduction your flame will have much less energy so 100 -200 f per hour will still be fast. Reduction has its nuances, but simplified, very dirty flame, slightly pressurized kiln not allowing any oxidation. Reduced pieces can and often are reoxidize by plain old air going past them if the kiln is not kept slightly pressurized while in reduction. Onlya handful of metals are affected by reduction. without an O2 meter, you fire by eye, reduction flame poking out spyholes Really nice example reduction flame below from an updraft. Firing with someone who is used to reduction firing is generally a patience saver.
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Bill Kielb got a reaction from Hulk in Down Draft kiln questions
Really good to have the combustion background, definitely half the battle. Now some stuff that may help with your background and hopefully allows you to work through the design and tuning. In the end It’s pretty simple basic combustion stuff
The split between primary air and secondary air is about 50% Knowing that will allow you to figure reasonable over cuts around the burners where secondary air will enter, if not 1– 2 inch clearance is fine. Too small is generally the mistake. An ideal ratio air / fuel will be approximately 10:1 (oxidation) Reduction will be a dirty flame, producing lots of carbon monoxide and ……… pressurizing the kiln so very little air is drawn into the kiln through the over cuts. Reduction is achieved by closing the damper and and pressurizing the kiln from top to bottom. Very slight adjustments will establish this. Slightly pressurizing the kiln (very slight) will be enough to keep secondary air from coming in the over cuts which drives the kiln into reduction. (Very dirty flame - no soot needed, too rich and decreases reduction) Never go into early reduction below the PEL of the gas 1500 f or better. #60 is pretty small as most propane kilns are regulated down to inches, but at .#60 (for now) you likely will operate this in the 1-2 psi range, here is one of my favorite orifice tables https://www.gordonpiatt.com/wp-content/uploads/2021/07/Propane-Orifice-Chart-7.E.80.6-Rev-3-05.01.pdf easy to figure just what pressure you will need after you figure how much Btuh you need as well. Total guess, start at prox. 300,000 btuh, work your way down as practical.The kiln will be easier to fire and adjust in firing using low pressure. Inches of wc pressure Design your flue by table p41 here can help or 4” - 5” is likely reasonable and allow you to tune the height in the end. https://www.selkirkcorp.com/literature/Chimney_Venting_Sizing_Handbook.pdf Higher increases draw but also makes damper adjustments more sensitive. For an updraft kiln placing the thermocouple as near the kiln as practical in the flue likely give a decent reading of the average temps. Gas kilns are fired supervised by cone so watching when cones bend will be more important than peak temperature. Firing rates 500-600 f degrees per hour are generally considered fast for clay, but once in reduction your flame will have much less energy so 100 -200 f per hour will still be fast. Reduction has its nuances, but simplified, very dirty flame, slightly pressurized kiln not allowing any oxidation. Reduced pieces can and often are reoxidize by plain old air going past them if the kiln is not kept slightly pressurized while in reduction. Onlya handful of metals are affected by reduction. without an O2 meter, you fire by eye, reduction flame poking out spyholes Really nice example reduction flame below from an updraft. Firing with someone who is used to reduction firing is generally a patience saver.
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Bill Kielb got a reaction from Ben xyz in Matte Sealer for Velvet Underglazes?
Hmm, I don’t not know if I fully understand. Underglazes are not glaze and often consist primarily of clay and stain. Many do not really melt so unglazed they are very matte but more sintered than melted hence durability or longevity would be difficult to guarantee. For a gloss finish it’s common to apply clear gloss glaze over the underglaze. For matte appearance with reasonable durability it’s also common to use matte clear glaze over the top of the underglaze. Any clear matte will cloud to some extent because of the diffraction of light. Thin application definitely better than thick as far as glaze clarity. As far as a glaze that works for you and your clay and the desired finish you will likely need to test.
If you look on Glazy.org Marcia’s matte https://glazy.org/recipes/19734. Was created to be very dry ( but easily adjustable) and melt over fairly heavy underglazes. It has great reviews, but it may not work for your clay, desired aesthetic, etc…. Sadly clear glazes often tend to take testing to meet an artists needs. There are many matte glaze recipes though - which one works for you will require testing.
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Bill Kielb reacted to Mark C. in Is it possible to use high-temperature engine paint on bisque?
The answer is #3
#5. The kiln will stink more than usual as well
# 6 try it and learn .
School of hard knocks has the best lessons