Not many potters are brave enough to talk about a failed wood-firing. Here’s an exception. Several weeks ago, I received an email from Sim Taylor with questions for his small anagama. He attached a photo image of his anagama and it was the ‘smallest wood-fired anagama’ I have ever seen. I rather liked his idea of the very small anagama and our email conversation has started. (Gas)
Thank you for the insights into your Kiln Building which has led to much visual inspiration and motivation in my own practice. Over the last year I have also been planning, drawing and building my Very small Anagama (Chīsana kama? )Would that be correct?). Only lately have I found out that you have also been on the same venture. I wish you well in your final stages of building and we wait in the anticipation of your 1st Firing. Early tomorrow my Anagama will have its first firing. I feel very excited but also quiet and peaceful in mind contemplating this 1st Fire. If you wish I will let you know the outcomes and very much appreciate your opinions.
Although I (am a small Japanese) can’t get inside of it, the kiln looks very nice and should work fine. Your ‘Chiisana-kama’ could be ideal for Raku tea bowls.
I am just wondering what sort of temperatures you are aiming at. And I hope you stick to it for a while until you really feel that you need a slightly bigger one.
Please let me know the result of your firing.
Please find attached some images of my new small kiln.
I fired Chīsana kama two weeks ago and I am only now starting to collect my thoughts. In short the Kiln went up and came down! There are lots of questions I have regarding the kilns performance as the unloading revealed generally unsatisfactory results: celadon/shino underfired and Clay colours were bland. The kiln was very uneven in its temperature from 1300 C bottom front, 1280 C top front, Mid zone cones at 1240 C melted and back zones I feel hit 1200ish from the semi fluxed matt glaze surfaces. Much I will put down to learning, whether this is Kiln design, Firing methods, Clay bodies and human errors. I fired over 18hrs and the last 6 hrs were highly temperamental with little Kiln response when I explored different stoking methods.
I now question whether I should alter the kilns endou, lengthening the flue to enable the chimney to draw better and help even-out the pot chamber?(the chimney got very hot and took days to cool). Another thought revolves around raising the grate area so embers are allowed to build up to generate more coals, storing more heat in the fire box. I definitely know that I need to experiment with new Clay bodies and also concentrate on my stoking methods to better reduction. One area of relief is that I know the kiln was serious wet and has not dried out at all due to this year’s weather, the kiln location is also built close to a soak away (this was intentional to allow the kiln to become regularly damp to induce better reduction from water vapour).
I built my new Anagama hoping that it would be fast fired Kiln, enabling me to get to high temperatures and then to develop surface textures and ash melt. Due to time being divided between my duties as a Ceramics and Art Teacher alongside my practise as a Maker a fast fire kiln seams appropriate. Over the last 12 years my work has been predominantly Saggar fired, previously I had built and fired other wood kilns including 2 Anagamas. I now want to return to Wood firing to develop Koge effects on my Ceramic Forms and Shizenyu on my Tea bowls.
I now start the process of learning. I will fire again in April.
Any thoughts on Chīsana kama would be much appreciated, in return if I can help or assist in any hard work it would be a pleasure.
Thanking you and take care
I have a few ideas to improve your future firings. Your kiln seems to lose heat easily and not not holding it steadily. I used to have the same problems with my mini-anagama and raku kilns.
I would like to ask you a few questions first. I can guess the size of your kiln but it is easier if you give me the measurement of your kiln(s) or more photos from different angles.
Also I was just wondering if I could upload your email on my blog and give my opinions. There must be many potters and wood-fire enthusiasts with similar problems. I can only give my answers from my experience with my anagama firings. I didn’t have much of the problems you had from my anagama, . So I can ask ask potter friends through my blog, We may get other experienced wood-firers advice. If you don’t like my idea just let me know.
Thank you for your support and I much appreciate your suggestions to place my kiln problems onto your Blog site. This would be a great honour for me. I also agree with your comment that this topic could and would help other Potters with similar Kiln problems. In this context I see your request as a great opportunity for experienced and amateur wood firers to converse, discussing ideas, sharing knowledge and so building confidence.
I will gather information together and try to scan my Kiln Plans with measurements and accompany this with more photos (I will need to compress and resize photos along with scan designs this week at work (College) I am limited at home with a very old computer). As soon as I have done this I will send.
The ironic thing in this scenario is that my last kiln (mini type gama) see attachment) I called the Kiln Urbangama because it was built at home, in town). It fired in 6hrs to 1310 C. My new kiln was based on a similar, scaled up design!? Hopefully we can find out my miscalculations.
As asked I have taken more photos and also attached 2 drawn Kiln diagrams with measurements. I hope this provides you with enough information to give you ideas on why Firing was problematic.
Further Kiln information that may help:
As mentioned previously the Kiln is built close to a soak away that drains water from the Workshop Roof that the Kiln is located next to. This has made the kiln very wet. The Kiln has no shelter (a temporary shelter is put up when Firing).
The kiln is built on a 1 in 10 foot slope.
I’ve built the kiln from old secondhand bricks from old dismantled Kilns and also industrial Chimneys.
The Fire Box is completely built with Super Heavy Bricks, the Chimney is built from bottom to top with Super Heavy, Heavy, to red Engineering Brick. The interior of the Pot Chamber is constructed from HTI bricks. The Whole Kiln Arch is also built from HTI Bricks. Kiln floor uses Heavy bricks. The Arch of the Kiln has an Insulating Coat of 3 to 4 inches of 1 Ball Clay to 2 Sharp Sand.
The Kiln is fired on free Palette wood, mainly Pine with some mixed Ceder.
The Kiln has a grate and ash pit that is 9 inches deep to collect the Palette wood nails (that have not been discarded in wood preparation) This area also supplies ample preheated air.
The Kiln has a blow hole half way along the top of the Kiln, but this firing I used this hole for my pyro/meter.
Information on Kiln behavour when Firing that may help:
Pyro/meter used + Cones.
12 to 14 hrs preheating gained 50C.
2 hrs good steady climb to 250C
3 hrs gained 500C with no specific stocking method, lots of stream off Kiln.
After 7 hrs 900C gained by loading & half filling of firebox
920 C ish Kiln roars on stoking. 1st sign of Flame viewed through chimney spy hole.
9 hrs 1020C. Temp slows down on pyro reading. Top 1154C Cone bending. Bottom 1050C Cone down.
Needing to increase amount of fuel to get rise on pyro. Loading & 3/4 Filling of firebox.
10 hr Flame out of Chimney. Stream off Kiln stops
11hrs pyro reads 1085C. Filling 3/4 of fire box. Heavier wood being used to maintain embers.
Here after all pyro readings over next 7 hrs vary. Hovering around 1079 to 1119C.
Had instincted to start feeding wood under grate to block up front of ash pit to gain more ember build up in fire Box. Kiln responded and started to pulling better. + Blocking off 2 out of 4 primary air holes off.
12hrs 6 foot flame out of Chimney! thought this was not good!? and no temp rise in next 2 hrs.
14hrs started using more medium size wood and half filling fire box, Kiln responded and pyro read rises back into 1100sC. Chimney flame backdown to 2 foot.
15hrs 1240C Top Cone down.
Blocking remaining 2 air holes by half. Using more wood but load being used up very quick.
15hrs Fire box Colour Yellow White.
16hrs Between each stoke pyro reading drops from 1100Cs to 1000Cs and back up to 1100C! Fire Box Colour back to Yellow Orange.
17hrs Top front Cone 1280C down, Bottom front 1240C down. Middle Cone 1154C down, 1240C standing.
At this point I decided to End the Firing due to the difficulty and problem solving in Stoking patterns. I also wandered whether I had packed the kiln in such a way that I had restricted air flow? With so many questions in my head I assessed that it was best to Close the firing and evaluate the experience for a next Firing.
I thought it wiser to stop than try to progress with at times a too confused mind.
I much appreciate your warm support, and above all I hope you find this interesting.
Wishing you well
Your photos tell me that you have two locations for your own small anagama. Do you have 2 kilns or did you move your kiln from one place to another? Every wood-fire enthusiast wants a small anagama in the garden. I am sure your kiln design will become popular when some problems are solved.
I will write my thoughts for your ‘Chiisana Kama’ and upload my post very soon.
Yes I do have 2 Kilns. Building Kilns started when I was 17 yrs, whilst at Art college I stumbled upon a book called ‘Raku’ this literally fired up an enthusiasm and long journey fascinated with Clay with Fire.
During my Art Foundation studies I built 3 Raku Kilns however later realised that I was far more intrigued with high fire and this started a love for building more sophisticated Kilns.
My passion was high but naivety made progression slow as I constructed my first down draft kilns at home whilst I studied Ceramics at Falmouth College in Cornwall.
By fortune, enlightenment came when I started my degree at Farnham College in 1989, under the guidance of Sabastian Blackie. Sebastian invited many inspiring Potters/ Ceramicists to enthuse his students. Two standout above others: Takashi Yasuda for this ability to observe and teach personally in his intense Throwing Workshops and Patrick Sargent who mixed/made Clay by foot and talked about Fire, building Kilns and walking in the woods and on hills before the inevitable solo 3 day firing. Inspired I was!
I left Farnham being able to Throw and with an understanding in Firing Wood Kilns. After my Degree, I built a 120 cubic foot Anagama with Burry Box inspired from our teachings and experiences with Patrick Sargent. This kiln fired perfect in 24 hours. I fired it 6 times but it took me 4 months to fill and prepare for each firing; eventually this did not suit my creative needs and thereafter I started building a smaller Anagama. Thereafter through circumstances I had to move away from Wood Firing and so for 12 yrs I’ve Fired with Saggar Techniques. I am now delving back into Wood Firing.
In answer to your question, I now have 2 Small Kilns. 1 at Home in our yard which I built 2 years ago inspired from Akira Yoshida’s minigama experiments. In Summer 2009 I set my students a Designing, building and Firing Minigama Project this was very exhilarating, see Youtube films:
Firing Minigama and Minigama Class Project 2009.
This event encouraged me to adapt Yoshida’s Minigama kiln and make my own fast fire Anagama with a small chamber of 5 cubic feet. This fires on wood to 1150C, then Charcoal and wood with assisted air to 1320C. The Kiln fires in 6 hrs which is convenient because neighbours do not like too much Smoke. Often, much of these wares are immature and so I also refire these Works. I have had some pleasing Hibuse wares at front and at the rear of the Kiln Shizenyu results, see attachments. I call this Kiln Urbangama because I live in a town.
This Tiny Kiln has led me to create my latest Second small Anagama now called ‘Chiisana Kama’. This Kiln is located in the town quarry 1 mile away from home. The kiln is a larger copy of Urbangama and has a chamber size of 15 cubic feet. I built this kiln because I needed a larger Pot Chamber to accommodate the size of my Ceramic Work, but also to inspire and encourage my students in the ways of Woodfiring. This is the Kiln I have had firing problems with and have sent though Images and plans. (the image of me is with my Urbangama Kiln)
Many thanks Sim for all your information. I have never receceived emails with details of othe potters firings. I am impressed with your sincerity very much.
When you sent me your email with a photo, I was surprised with the sise of your ‘Chiisana Kama’ as it looked smaller than 3 meters (10 ft) long. My initial thought was “Would it work?”. I have always tried to build wood-fired kilns over 4 meters on a slope. So your ‘Chiisana Kama’ [mini-anagama] was a quite new and fresh idea and if you make it work properly. You said that your chimney got very hot and took a few days to cool. That could suggest most of heat has quickly gone passed the pot chamber. The difference of temperature also show the hot frames might be runnig along the ceiling of the main chamber and that made the the big temperature gap between the tpo and bottom in the chamber. I could not see any proper flues at the back of the pot chamber and I didn’t like the look of the damper, if you don’t mind me to tell you.
With a small kiln, I would try not to have a big damper and definitely try to build a ‘Sutema’ [I call it ‘waisting chamber’ in English as Japanese word ‘suteru’ means to throw away, to desert, to abandon and to sacrifice] instead that may stop the heat and retain it in the pot chamber. ‘Sutema’ doesn’t have to be big and you can easily build it at the back of the main (pot) chamber with 2 walls with flues. It is like a small empty box (with 30 cm empty room between the 2 walls) where hot air lingers in there for a just while. As ‘Sutema’ gets very hot, some potters try to fire some pots in there by making a side doooron the kiln wall. I don’t recommend this for your ‘Chiisana Kama’. It is a waisting chamber and has to be sacrificed and waisted. If you still think you really need to have a damper somewhere why don’t you have it at the back of kiln some where on the chimney.
I do have some other ideas that may improve your firing a bit but you should not apply too many changes all at once. Try one change (one new idea) at a time.
You also try to fire your ‘Chiisana Kama’ as fast as possible. I understand that and it would be wonderful if you achive your aim with your short firing on your planned chart.
How long exactly you would like to wood-fire?
I do admire your challenging sprit. You might need to consider futher alteration for your firebox design or your way of packing ‘Chiisana kama’.
Use your common sense and wood-firing can be done with a simple ‘anagama’ but it is rather temperamental. Success only comes after many long days of tenacious work coupled with a good understanding of surrounding nature.
I really wish you good luck and all the best with your next firing.
My anagama firing is a long firing and usually takes 9 – 10 days. I believe woof-fire has its own nature and I don’t expect my kiln to behave as I hope, so I just wait until my kiln decides its temperatureto go higher. That is one of the reasons I stopped using Pyrometers and corns. I just try to enjoy the firing in the woods.
And if I have to make my pots wood-fired quickly and successfully, I would rather try to design and build a Fred Olsen type of kiln.
And there must be some wood-potters had the same problems and situations but managed to ovecome and now doing alright. Please let us know your experience.
I received another mail from Sim for the reply to my thoughts.
Regarding Chiisana Kama. Thank you for your time, thoughts and sharing of your Kiln knowledge and experiences supporting me with my practice. It is a rarity that people want to help others nowadays.
But in short I must say….. this is really exciting! Thank you very much for your suggestions.
It is interesting reading your ideas and ways to woodfiring, long firing and natural progression allowing the Kiln to find its own way, as different to my rather forced and crude ideas to fire fast. The suggestions you have made sound gental, positive and a passive means to my problem. Your great mentor Furutani, writes of ‘Sutemas’ but you have explained and expanded upon how this kiln area works by emphasising that it is a ‘waisting chamber’. I have always used, what is termed as, a ‘collection box’, an area at the bottom of the chimney that is slightly larger than the chimney cross section that acts in allowing flue gases to correct themselves before they channel up the chimney. But what makes sense is that a ‘Sutema’ is divided betwean two flue walls, It feels that this would create a back pressure and holds back the hot flames, building up heat in the Chamber. I like this idea. Am I right in my undersanding ?
I did started my own calculations.
A few days ago I started this e-mail to you:
28 March 2014.
You said to me that you think that the irregular temperature is due to the Kiln not holding heat and on this basis I keep thinking I should focus upon slowing the kilns draught down to keep the fire more in the Kiln, so either:
Lower the chimney from 8” to 6” ?
adjust chimney and exit flue dimensions in relation to fire box size?
With these thoughts I have gone back to Fred Olson’s kiln principles to try and make sense and calculations (I say try because my Math is not that good).
Olsen says that the Fire box should be 10 greater than the chimney cross section, 10 to 1.
My Firebox is 1320 square inches divided by 10 = 132 square inches = 11 1/2” x 11 1/2” Chimney section. My chimney section is 81 square inches or 9”x 9 ” Chimney section. Therefore it appears that I need to rebuild the chimney to be larger from 9”x 9 ” to 11 1/2” x 11 1/2” ?
I am not sure whether these small adjustments will be affective, although I guess because the kiln is Tiny then the ratios will also be very small.
In addition I also am wondering whether I should alter further Exit flues? The dimensions are as follows:
Exit Flue =9” x 11”, into Collection Box (at base of Chimney)= 13 1/2” x 9”, which tapers into Chimney = 9” x 9”.
Here, I could alter the Exit Flue by removing the Damper Gate. This would make the
Exit Flue slightly bigger = 9” x 14 1/2”, into Collection Box remaining the same = 13 1/2” x 9”, which tapers into adjusted Chimney = 11 1/2” x 11 1/2”.
Do my culcalations make sense or am I really off the scent? (here ends the 28 March Email)
So I have had lots of thoughts and am now motivated to work on this challenge.
In answer to your questions I need to fire in 24- 36 hrs max’ because the kiln is located in a public space and I need to limit smoke down to a minimum. My plan is to fire fast to Stoneware Temperature and then soak to mature ash melt and matting.
I also agree with your thoughts on not liking the damper. The Damper was placed in originally to act as a way to alter the exit flue dimensions, not as a devise to prompt reduction. (In my 2 previous Anagama’s I have never used a damper- I have only used dampers in Downdraught kilns)
I would say here that I feel greatly honoured with your interests in Chiisana Kama. I will take your advise to build a ‘Sutema’ between the chamber and Chimney, as I can feel and visualise this solution above others.
Can I send you a drawn plan on a Sutema design for your approval?
This is an update of Sim’s post.
I was also fortunate to catch Svend at home and although I have spoken a few times I have never had the opportunity to talk in length about Kilns. I drove down familiar Lanes, passing small copses, up and down and dodging cow splattered potholes. Finally sighting two tall firebrick chimneys, tell signs, for some, of Woodfiring Kilns. I pulling up in front of the Svend Pottery.
On your guidance to build a Sutema and the description you give of a contained area divided between two walls I keep thinking of previous sightings of other kilns with similiar devices located at the rear flue exits between Chamber and Chimney. In my first Kiln built in Priddy on top of the Mendip Hills, Somerset I used a Chequer wall taken from speculation and copying Patrick Sargent’s ideas on remembering his lecturer and designs on the building of his Burrey Box Anagama, The ‘Mule’. I have not built such a devise in Chiisana Kama because I simply thought that a chequer wall would block the flow of gases/flames leaving the kiln. Although now it appears that the flames are leaving too fast and they need keeping in. In conversation with Svend he was very interested in your thoughts on this matter and agreed that the kiln needed slowing. He related the path of the flame to the nature of water and that it would always find the easiest way to flow. Here I can visualise how a Sutema could slow the flame but also direct the flame down from the kiln roof and lower into the chamber, hence distributing the heat.
After what seemed like minutes but turned out to be over an hour Svend pointed to one design (Design C) he favoured. This has an extended Flue chamber that is 50cm in internal lengh and is walled by two chequers. However, and interestingly Svend said that he would only use the rear Chequer Wall and not both. He did insisted that their should be air inlets in the Sutema to control and combust the waste gases and here he spoke and we discussed ‘Passive Dampers’. This talk also led to talk on how allowing air into the Sutema-Waste Chamber could also effect and even control the amount of reduction present in the kiln?
I much appreciated Svends advice and the sharing of his knowledge and telling me of some of his experiences regarding Sutemas. Thank you Svend.
The sun shone fantastic in Weston Quarry today as I took down my kilns Chimney. I’m really excited to be adjusting the Kiln so she can work properly so myself and others visiting Weston quarry can experience and enjoy Woodfiring.
Gas, please inform me of your thoughts and ideas on my Sutema drawings. I will start building the foundations tomorrow. I look forward to your reply.
As it seemed he needed my quick reply, So I asked Sim to phone me in the evening. We had a further discussion about ‘Sutema’ on the phone. (Gas)
I never thought about anagama smaller than 15 foot (4.5 meters) long. My challenge has been rebuilding mediaeval anagama as much original as possible and reproducing beauty of mediaeval anagama vessels. I didn’t have many problems once I found kiln-site with proper inclines for the kiln floors. Only a few of my own ideas have been added to the kiln projects, so (I must admit) I could be called another conventional kiln builder.
I did not want to suggest a big change for Sim’s kiln design. So my suggestion is a tiny alteration to his kiln design. It is Sim’s own design and his own challenge that I should not put too much information into his head. ‘Sutema’ is a very good system to have when a wood-fire kiln is a little bit small and not having proper floor incline. ‘Stema’ should help Sim’s kiln ‘Chiisana kama’ work better but proportion has to be carefully considered.
I would like to visit and see Sim’s small angama working properly when he solved the problems with his design.
All the best with your project!! Sim (Gas)