Kiln Building & Human Psychology.

[Jose]

First & foremost, thank you for reading and thank you for your time. I got the OK to build a kiln... and I'm a mental mess!!!

I'm excited because of the possibility of wood firing, and nervous because of finances and the fact that I've never built a kiln; Afraid of burning the forest down! Commented to my supportive wife how I subconsciously wanted the landowner to reject my request, so that I may endeavor in a less daunting task... I've never wood fired before, much less build a kiln! Majored in ceramics and my mentor was Korean/Japanese, and she got me hooked on wood fired aesthetics. We had a gas kiln and would fire my work in saggars with lots of sea materials... it was enough for me.

Crazy mental & emotional roller coaster!i've dreamt of having a wood fired kiln since my 20s (43 now).  Many things happened since then (life really). The dream was deferred and it has festered like a sore! It was so bad i literally could not look at ceramics without thinking What If...

I processed all that stuff long ago. But now i have this opportunity, and I'm an emotional hurricane. Is it just me, or are most of us scared/fear our potential? Fear of failure or success? Simple fear of the unknown? Fear is the wrong word for sure... more like anxiety/nervousness. My wife is the writer, not I. I think the financial reality of building a wood kiln hit. But, honestly, like my wife has asked, how much are our dreams worth? I live in a heavily wooded, and very rural area in an old/historical wood heated home, so wood gathering/prep is no concern. 

Here's where I am not so confident and need some feedback. I have a background in heavy construction, so i've figured lots out about brick builds, but conceptual understanding and actual doing are different things. The basic brick laying, mortaring and all that is no problem, but i'm facing design issues.

Kiln builders, what's the best/good build for flashing and ash build up? I'm assuming a sort of tube kiln, but that would require a great deal of bricks; though i understand this depends on size of course. I am currently thinking about a small 15 - 20 cu.ft. double cross-draft sprung arch. However, not sure if this would result in the types of ware I'd like to make. Have looked at and read about kiln design and history and have several books arriving soon. @Mark C. & @neilestrick and others i cannot remember, i have read many of the post on the forum about kiln building and you two really drove home the point of not skimping on quality materials and getting the right tools/materials for the job. 

Looking forward to hearing from you folks on technical & psychological issues discussed. I'll start putting photos as the build progresses.

Again, thank you for reading this and thank you for your time. 

 

Edited May 16, 2022 by Jose

[Mark C.]

If its a wood kiln there are a few web sites for wood firing only and thats where you will get the best info on this type of kiln. I have done wood firing and once made a fast fire wood kiln in the 70s. Never a cross draft.I have friends with them and they work well.Wood fire is a hard brick kiln for sure. High fire hard brick.  Lets see and lots of bone dry wood as hard brick absorbs heat like a sponge. A good back and lots of drive and coffee and  tons of friends thats all that  is needed. At 43 you can jump in with booth feet-a good pickup truck or flat bed will be a good deal as well.

[Hulk]

Road trip, err, trips!
Get out thar an' visit some wood kilns and the people that built and run them.
Good for you Jose! Jump, for the train runs swiftly, oh so.

Wood fired near Grand Canyon, hrrmmm...

Enchanted Circle - perhaps a bit far
Rietz Ranch
NAU (wow*)
AIA Society of Tucson
Arrowmont Light It Up: Wood Firing the Train Kiln - Arrowmont School of Arts and Crafts

Please do post your progress.

*are you seeing this? Seven wood fired kilns
...doubled back and copied the link Ceramics facilities | School of Art (nau.edu)

[Jose]

@Mark C. Working in getting a pick-up. If you don't mind, what are those wood fire specific sites? I've dug and only found sidestroke ( very old site). Thanks Mark.

@Hulk I just found out about Reitz Ranch and will definitely road trip there. NAU is a hotspot for wood firing and it's about 2 hrs away. Unfortunately, they haven't been very welcoming to non-students. I'll write something so they might have more time to see & process my intentions/ request. Initial shock, nervousness, doubt have given way to excitement and optimism. I  got some road tripping to do! 

Anyone know what design type is best for flashing & ash build? I think a tube kilns is it, but squared sprung arch is a simpler build. 

Wishing everyone & their loved ones the best.

[Mark C.]

Just type this in your browser

wood firing pottery websites

Edited May 17, 2022 by Mark C.

[neilestrick]

If you're going to be firing it by yourself, or with minimal help, then I would look at a design that fires quickly and efficiently, but creates a lot of ash, like a simple cross draft. A tube kiln requires a long firing and a lot of wood because that design is not efficient. I fired a catenary arch cross draft a lot in grad school, which burned about 3 pickup loads of wood (midsize Nissan pickup) in 13 hours, and produced a lot of ash. The catenary shape limits sticking space near the top, so if you wanted a little more volume I would use a barrel arch. The round shape would be better than a sprung arch in helping with air flow. Make half the width the firebox, the other half the stacking area.

[Jose]

@neilestrick After a week of intense research, I had decided the cat arch would suit me best. Outside opinions convinced me that a tube shape would be better!  OK, sure, their logic made sense. Well I just got back from NAU ( much better experience this time), and the kiln builder there recommend what you just posted!!! It seems that for backyard kilns a cat arch offers lots of benefits. Neil, must the fire box take up 1/2 the width or can it be less? Is this dependent on kiln size? Thanks.

[neilestrick]

9 minutes ago, Jose said:

@neilestrick After a week of intense research, I had decided the cat arch would suit me best. Outside opinions convinced me that a tube shape would be better!  OK, sure, their logic made sense. Well I just got back from NAU ( much better experience this time), and the kiln builder there recommend what you just posted!!! It seems that for backyard kilns a cat arch offers lots of benefits. Neil, must the fire box take up 1/2 the width or can it be less? Is this dependent on kiln size? Thanks.

Is Jason Hess still at NAU? I went to grad school with him. He built the cat I referred to.

Tube kilns are sexy, everybody wants one. They love the drama of the long firing and the history of that type of kiln. But they're not ideal unless you have a team to help fill it and fire it,and access to a lot of wood. Tubes are a lot harder on the body to load, too, climbing in and out. Plus they are far more complicated to build. Building a crossdraft is just like building a gas kiln- firebrick, cinderblock, and angle iron. Two people could build it in 4-5 days.

The firebox could be slightly less, but the large firebox to stacking area ratio is what allows it to produce a lot of ash and fire quickly.

[Russ]

One thing to think about is that wood fired kilns are unbearably hot to be around in the warmer months. Mine is fired in the colder months of nov thru mar.  I considered this when I built mine and went with a large size to accommodate a large amount of wares.

About ash buildup. Choose woods with a lot of bark attached . The bark is where most of your fly ash will come from.

PM me José  and Ill send some pictures of mine.

[Jose]

@neilestrick Holy smokes, you know Hess? Yeah, he's still at NAU! I had a much different experience this time at NAU. Hess seems like a good guy. OK, I get the large firebox to stacking area ratio. Neil, are barrel arches self-supporting? I'll research this myself, but thought i'd ask. You still keep in touch w/ Hess? Wow, small world! Thanks for the feedback.

@Russ Thanks Russ. Fire restrictions just started here, so I will not be doing any firing in the next 2 months. Living in the high desert, there's no way i'm going to mess around w/ fire during the summer or spring months for that matter. You're in Santa Fe so you know. Wow, I got lots to learn about wood behavior & combustion. I moved here during the dead of winter into a wood heated home! I've had to learn a lot about gathering and prepping wood, but it still seems like I have lots to learn. Thanks for the feedback and offer. I'll take you up on it. Best wishes.

[neilestrick]

40 minutes ago, Jose said:

You still keep in touch w/ Hess?

Unfortunately, no. We both got busy with life after grad school. He's a great guy, though, taught me a lot about wood firing.

41 minutes ago, Jose said:

Neil, are barrel arches self-supporting?

In theory, yes. In reality, it wouldn't be safe to build one without an angle iron frame- 2" angle at all the corners, and 3" or 4" channel along the arch skews (not that a barrel arch has real skews). I'd also add a couple pieces of angle or channel along the back side of the firebox to help keep the bricks in place if you toss a piece of wood in too hard.

There are lots of different ways to do the door, everything from hinged to rolling to just hanging it from a chain.

One way to deal with the heat coming off the kiln is to build the kiln with a hard brick interior and soft brick exterior, or add some rigid fiber board to the exterior on the side where you'll be standing.

[fergusonjeff]

I built the type of cross-draft kiln in Neil's drawing a few messages earlier.  Works really well.  Not always a lot of ash build up, but you can supplement with sprinkled ash prior to firing.  Works really well for glazed wares.  I can fire it in under 10 hours to well over cone 10.  Just fired it yesterday and that will be my last firing until fall.  Not fun to fire in the summer (heat stroke last time I tried) or the winter (10+ hours outside in the cold).   I have fired it about 25 times and getting better results each time.  I just fired it yesterday so waiting for it to cool to see how it went. 

The version I built is about 18-20 cubic feet.  Anything smaller would be very difficult to fire.

There are very specific plans for this published, but I am forgetting to book.  If you are interested I can get the reference. 

[GEP]

I agree with @Russ that bark is essential for developing ash. However, your wood source will depend on what you can get near you, and cheaply. You need a lot of wood, so “cheap and available” are more important than “specific.” 

Wood that is processed to be clean is good for developing heat, but not great at providing ash. I fired several times at a wood kiln that used old pallets as the heat source (very processed wood) so we supplemented it with bark mulch from the hardware store, to create more ash. 

Edited May 18, 2022 by GEP

[Jose]

@fergusonjeff Sorry to hear about the heat stroke. Yeah, I don't plan on firing during summer months. This area is under fire restrictions during that time period. I've heard it from several sources already, and I am really happy to hear this kiln design works & is very versatile. Dimensions i'm looking at put me at 15cu.ft. not that far from yours. Thank you for sharing your experience w/ it and yes, if you can remember the book or reference, I'd love to know. Best wishes.

@GEP Trust me, I have all the wood i could ever need! I'm fortunate & grateful to have access to several saw mills and mounds... and i mean mounds of sawdust, wood chips, lumber, branches, 6 - 24" rounds & logs, and an entire pine/juniper forest! Forest has way too much fuel!!!  It's been mismanaged, and the local Forrest Service office is more than happy to have folk trim it down. Anyway, I'm "spoiled" and very grateful. FYI, gathering wood from the forest is a TON of work, but I'm new to experience and i love it so far. Just not the first time i did it... that was probably one of the worst experience of my life!!! Thank you for your input on ash development.

[Russ]

I get my wood from a small lumber mill here. It comes in a 1 cord bundle and consists of small strips, an average of 1inx2in by 8ft. Cut into thirds its perfect for tossing into my fireboxes. Its pine so it burns very fast and with a long flame and doesnt have lots of bark which is what I prefer. .. it keeps the glazes much cleaner.  if you want ash buildup use larger pieces with bark which prolong the firing allowing more time for ash to settle on shoulders. Keeping in mind that the ash wont begin to melt till way late in the firing.

Oh and here in SF county a kiln is not considered open burning. Its more along the lines of a wood stove and is not subject to the burn bans.. this info from the fire chief who showed up during a firing many years ago. But check it out in your area for yourself.

[Jose]

@Russ Good tip on finding out what a kiln is considered. I am not taking risks though, besides I'm the park. Lots of rules; which i understand & respect. HA! That bundled cord sounds nice... the ones i get full rounds. Working on getting a splitter, though i enjoy the maul & axe work. Gotta admit, i take a parallel stance now when cutting rounds after almost driving the axe through my lower shin! 

[neilestrick]

11 hours ago, fergusonjeff said:

Not always a lot of ash build up

When I fired that kiln, I would take about 9 hours to get it up to about cone 8 or 9- just hot enough that the ash starts to melt- then hold there for another 3-5 hours, just burning wood to build ash. Then a final push at the end to cone 11 at the end to melt everything well. You can get it pretty snotty in 13-14 hours.

For wood we used lumber cutoffs from a local truss company- 2x6-8-10 boards- for the first 2/3 of the firing, then we'd use pine bark cutoffs for the rest. We had a local sawmill that bundled their bark cutoffs in 8 foot lengths and sold them $50 for 3. One bundle would fit in my pickup bed, one bundle per firing. Cheapest firings ever. This was out west so we didn't have access to any cheap/free hardwood, only pine.

[Rae Reich]

Great stories, guys!

Here in the city a gas kiln needs the same permit as a gas barbecue - none. Even so, I invited the local fire station over when I was firing my big old fire-breathing catenary and also to a raku firing (even got some sales). They appreciate knowing what’s going on and how to respond to concerned citizen calls. And they love fire, too., and appreciate when we treat it with respect. 

Edited May 19, 2022 by Rae Reich

[Pyewackette]

Congratulations on reaching your clay goals!  You managed it 20 years sooner than I did LOL!