Thursday, October 8, 2009

This week I have been mostly... smoking! Raku that is!

Some time ago I promised my little group of students a session with my Raku kiln. Unfortunately the weather did its best to rain on the days that we arranged to fire the kiln, so things were put off for a while. On Monday, things were fine here, so I did a test firing of the kiln in the afternoon, and one of my group came to watch the latter part of the proceedings. On Tuesday afternoon we were able to muster two of the three students, and so we fired some work. Toasted marshmallows were a feature of the afternoon, and the two cooks had their own thoughts as to what made a perfect toasted marshmallow. One preferred charred to perfection, and probably on fire, whilst the other took a more subtle approach, going for a light brown crust concealing a soggy interior.

Fire drill was practiced after the firing. Well, the stirrup pump did need to be emptied!

Today, Thursday, I did a firing of my own work. I was impressed with the results of the firings on Monday and Tuesday, and have to send some new work to a gallery tomorrow, so... I thought the Raku kiln might add a bit of magic.

Light to moderate rain actually proved pleasant to work in, and gave atmosphere to some of the photography. Laura took most of the photos of the event.

Very occasionally I managed a brief sit down, but firing a Raku kiln is demanding, and most of the time I was feeding wood into the firebox, and watching the temperature go up, drop, then climb again. Every new piece of wood gave a noticeable dip in temperature, before climbing away.
Our alarm clock kept a watching eye over events. I find it very helpful to mark the temperature on graph paper every quarter of an hour, to measure progress. This kiln will get to just over 1000 degrees Centigrade in just under two hours. I fired to 1050 C for this firing.

I fired quite a lot of the time in reduction, that is a somewhat oxygen starved state. I hoped to add carbon to the unglazed clay, and to turn copper greens red. The flame coming out of the spy hole shows a reduction atmosphere. That poor flame is hungry for oxygen and will get what it can outside the kiln if it can't find enough to satisfy it inside.

At the start of the firing I build up a fire in the ash pit. As temperature builds I establish a fire on the grate.

At 1050 degrees Centigrade I open the chamber door. You can see the bright river of fire rushing from left to right. There appear to be several phoenix birds in the kiln!

I take out each object from the kiln.

Each pot is placed on a square of newspaper, and a tin with some shredded newspaper in it is placed over the top. After about 30 seconds the tin is slightly lifted to admit some air. The paper immediately ignites, and, when it is burning fiercely, the tin is pushed down firmly to cut off the air. The flame uses up all the air in the tin and the fire goes out. Meanwhile back at the kiln, a new load of pots that has been warming over the firebox is put into the still very hot kiln chamber. The door is shut, the kiln stoked, and the kiln quickly bounces back to 1050 degrees C.

When the pots have cooled down a lot, I remove the cans and I put the pots in a bucket of water, one at a time. You have to be careful with bottles, if they are very hot, water flowing into them can flash immediately into steam and eject boiling water with great force. Once the cans are free, they can be primed with shredded newspaper and be ready to cover the next load of pots from the kiln.

After the pots have cooled, they can be gently cleaned with a wire pad and Brasso, or some other brass cleaner.

In some cases, the oxygen starved atmosphere in the tin managed to turn the copper in the glaze, into a thin layer of copper metal. Where the reduction atmosphere was less severe, various shades of copper red were produced. Where there was plenty of oxygen, the glaze was green.

You can see from the varied colours how different parts of these birds received greater or lesser amounts of oxygen.

The underside of these little bowls shows the carbon impregnated unglazed clay around the foot of the bowl, and the shades of green, red, and copper are visible.

A new bird was seen in our garden today!

Here are most of the bowls and birds that came out of the firing.

Ginger found all this hard work quite exhausting, and rightly chose to go to bed!

*The word Raku is a Japanese word meaning pleasure or enjoyment.
**Raku -according to Wikipedia

14 comments:

Judy Shreve said...

What fun for your students to experience the Raku kiln - I've never participated in a wood fired Raku before. Wood certainly requires more energy from you!

I absolutely love the birds! Perfect colors.

traceybroome@mindspring.com said...

Well, you know that I am loving this post. The reds are just beautiful!! It's a lot of work isn't it? Great job!!

Angie said...

How fascinating that all was to read and almost observe .... and what amazing results. I love the colours that are produced and those birds are wonderful.

jimgottuso said...

made me wish i could have attended... haven't done raku in so many years but whenever i see a long post about it like this i have a tinge of nostalgia... all that fire... fun, fun fun. the pots came out great and looks like everyone had a great time including the cat.

cindy shake said...

Beautiful photos! The finished colors are wonderful :o) I love your kiln!

Peter said...

Hi Judy, Tracey, Angie, Jim, and Cindy, really lovely to hear from you all. Thanks for your encouraging comments. I haven't done much raku before, but it is a magical experience having things happening so quickly, and seeing colours change before your eyes. I do love the view that you get of all the pots in the kiln when the kiln door is opened. Really mysterious and beautiful. Firing with wood must be rather different than using gas (I haven't done gas raku firings yet). Wood does make for a somewhat tiring afternoon, but fun tired, rather than dead on your feet tired, which is how I usually am after doing a 13 hour stoneware firing in my larger wood fired kiln.

Jim, you'll just have to come on over one day and enjoy some woodsmoke!

In the next couple of days or so I'll put up one or two more close up photos of some of the work that a friend of mine took for me today.

Armelle said...

Lovely colors and lovely kiln......lovely cat

So you are so far away !!!

Wish to meet you

Arkansas Patti said...

Great post per usual Peter. I am reading intently along and then Ginger pops up. Quite a nice surprise.
I am always amazed at the heat you achieve.
Interesting how you can form a thin layer of copper. Always learn here.
By the way, I like my marshmallows crispy critters.

Peter said...

Armelle,
Thank you for your comments and welcome to my site. I have just visited your delightful site and seen your beautiful photos.

We hope to visit France one day, so, maybe we will get to meet you!

Best Wishes to you.

Hi Patti,
Lovely to hear from you. Glad that you have marshmallows over your way, when I mentioned them, I had a few doubts as to how much sense I might be making if people weren't familiar with them. It is fun writing for people all over the world isn't it!

Ginger pops up everywhere! Today I had a "play" of my accordion, and Ginger watched me with a look of horrified disbelief on his face. Almost pity! (Maybe he thought that I wasn't doing a particularly good job of killing what ever it was that was wailing and howling in my hands!) He followed me around the house as I played rather in the manner of a not quite full up shark thinking about one more snack!

Armelle said...

Thanks Peter, have you also visit this post about Gas and a wood-firing week-end in England. He shows how to built a little Raku kiln and fired two days. I dont live so far from England, in Britanny, in a little island. I was so impressed by Gas's kiln and wanted to meet him. http://blanc.bleu.over-blog.com/article-30802241.html and the post before and after.
You are welcome in Belle-ile-en-mer. I started to built the little kiln yesterday !!! I am quite a novice, in english too.

Have a good day
Armelle

Peter said...

Hi Armelle,

I did visit the post about Gas and the wood-firing weekend. I recently discovered Gas's website and am most impressed with his work and his wonderful kilns. How exciting that you are building a kiln! Your English is lots better than my French!

Best Wishes to you,
Peter

Linda Starr said...

What a great post, I love your blow by blow explanation and the colors you got ar wonderful. Those birds are so beautiful. I really must figure out a way to come over and visit you and Laura. I'll bet you felt just like Ginger (so sweet) when you were finished with all the work of the raku firing.

Peter said...

Hi Linda,
Lovely to hear from you. Glad you enjoyed the post, I was worried that having all those photos would be a bit hard on some people with dial up, but it was nice to try to share the whole experience.

Mmmm, reading about Gary and you buying an old bus and shifting from one part of the States to the other makes me sure that you will think of some way of visiting us one day. Maybe an old submarine could be used for transport! One way of crossing the ocean below the storms without getting seasick! Seriously though, it would be such a lovely thing for us to meet up with you both, we will see if we can make it happen some how.

All the best to you both, P.

Pat - Arkansas said...

Better late than never? I'm playing catch up for a few minutes, so just checked in to see what you've been up to. I greatly admire the results you achieved with your raku firings. Everything is beautiful; I especially like the birds.

One of our church members just returned from a trip to NZ and Australia. She is still slightly euphoric, and I don't blame her. I'm to see her photos tomorrow.