Thursday, February 25, 2010

firing the wood fired raku kiln video

We fired the wood fired raku kiln yesterday with just a few pots. I wanted to test some clay and glazes, so had pots made from 4 different clays, and tested about 4 different glazes as well. I lit the kiln at 9.10 am, and had the firing all over with and the pots out of the kiln exactly 3 hours later. The firing was to about 1050 Centigrade.

I have included 3 photos of the nicest pots that came out of the firing. The first pot has a simple glaze inside and out of alkaline fritt 4110 70 parts by weight, 18 parts china clay, and 2 parts bentonite. This has another copper bearing glaze brushed over it for decoration. I have used this copper bearing glaze by itself on the second pot, the recipe is as follows: Alkaline fritt 4110 75, China Clay 10, Silica 10, Titanium oxide 4, bentonite 1, copper carbonate 5.

The lidded jar has the simple glaze that the first pot had with the addition of some red iron oxide, about 5 percent. Wax resist patterns were painted onto this, and then the copper bearing glaze was poured over the outside and brushed on the lid.

I find that alkaline fritt 4110 is a very useful one for raku and for earthenware glazes. All that is required for a simple glaze is the addition of some china clay or some ball clay. Glaze fit can be improved by the addition of extra silica. I usually add 1 to 2 parts of bentonite to my glazes, this helps prevent the glaze from forming a rock like lump in the bottom of the glaze bucket, and also makes the surface of the glaze less powdery and delicate when it is on the pot before it is fired.

Just a quick post this as there are lots of things to do today, including fixing 2 holes in the living room floor, sorting out my studio, giving a lesson, and opening our gallery this afternoon....!

Sorry my glaze testing number 2 post hasn't quite happened yet.
I fired some stoneware chun glazed bowls in my electric kiln a few days ago, here are photos of one of them.



Following this should be a video of the wood fired raku kiln firing.


video


Firing The Kiln
When firing this kiln I establish a small fire in the ash pit and warm the kiln for about half an hour. At first I keep the fire box door open to allow cooling air through.

Once the kiln and pots are warm I close the fire box door and let the temperature climb to about 400 degrees centigrade. At this point I have a good bed of hot ashes in the ash pit and I am able to start a fire in the fire box above the grate.

The temperature climbs rapidly.

You will notice that I continue to occasionally stoke the ash pit as well as the fire box. This is to ensure good hot embers there to pre-heat the air going into the firebox. Later in the firing everything is so hot that this is no longer necessary.

I unload the kiln when the glazes are really shiny, this is at about 1050 degrees.

The pots are placed on shredded newspaper on a clear area that has a bed of ash and charcoal from previous firings.

Tin cans containing more shredded paper are placed over the smallest pots.

Larger pots are placed in bins, with tops sealed with damp newspaper, and a kiln shelf placed on top to stop the air getting in.

I allowed the pots to cool for two hours before looking at them.

13 comments:

Angie said...

What fun that video was ...felt I was there watching over your shoulder. The lided pot had a beautiful finish ...loved the shape

Linda Starr said...

OOOwee I need one of these wood fired raku kilns as soon as I get resettled, great stuff you are doing Peter.

ang said...

nice one pete, great to see the wood firing action, i'll be joining in with my mini kiln very soon!

Anonymous said...

Very nice too!
I hope you're bringing some crystal ware with you on Sat. It wouls be great to compare them with the photos - and make the others really envious!
Dad

jimgottuso said...

lovely pots peter... i enjoyed the video, reminds me of the raku days. lots of fun, aside from the spider, whose grisly death was imminent

Armelle said...

Thank you to share Peter, very nice video and great post. It seems more simple for me now and I will try again when the wearther will be better.
Wax effect is very interesting, we can see the background.
I like the first one and the chun glaze is beautiful.

Best wishes

Peter said...

Hello Angie,
Glad you enjoyed the video. I Wish we had been able to have shown more of taking the pots from the kiln (probably the most exciting part!), but we were both too busy at that stage. Amazing being able to share the sort of glimpse into our world that video brings.

Hi Linda,
I think we will have to design a wood fired raku kiln that you can tow behind your vehicle as you travel! Actually, I'm sure it could be done!!! It was very good to do some raku, so much happens quickly with a firing like that, it gets the creative juices flowing again!

Hi Ang,
Really looking forward to seeing your hi tech wood fired raku kiln in action. Looks like a great idea.

Gidday Dad,
We will arrive bringing gifts! Happy Birthday Mum! (and a slightly belated Happy Birthday to you too!)

Hi Jim,
We were thinking of you when we were firing the kiln. Laura wanted me to put some more atmospheric footage of smoke pouring out of the chimney and fire in the chamber as she thought you would enjoy it! Alas... poor "Yorick" the spider, what a way to go! I suppose any other spiders watching may have been speculating as to the chances of smoking improving the flavour of the deceased! Spiders aren't generally known for their empathy!

Bonjour Armelle,
I was hoping that the video might help you with firing your raku kiln, as I know that you were having difficulty getting to temperature. It will be nice when weather improves enough for you to try again.
Ginger and Laura send their greetings!

Eleanor said...

Hi Uncle P.

Was just watching your vid. nicely done. I noticed you haven't perfected your kiwi accent yet :P

The 1st pot looks awesome, and is def a fav.
I'm keeping pretty busy; yesterday I helped duct tape Ben's house together. That stuff works wonders.

I'm off to walk the puppy as the sun is shining here today. I think it's all of 8 degrees but after weeks of nothing above 3 it feels like a sauna :-)

Hope you are well.

Angie said...

Had to pop back to say ...when you have time,please pop by as there is something for you ...near the end of the blog xx

Peter said...

Hi Eleanor,
Lovely to hear from you. Mmmm, the Kiwi accent seems to come and go rather. I think what accent I have is rather a muddle from having lived both sides of the globe (I wonder if your own accent will change?!!).

Duct taping a house together sounds just my sort of repair job... I'm impressed! Car "bog" works really well in rotted window sills and holes in walls!

It is funny how 8 degrees can feel "warm", but when the sun is out, and there is no wind blowing, it can be very nice indeed. Indoors I find 12 degrees OK for working at the wheel, but 10 and below become a struggle with the sleeves rolled up for work... you end up colder and colder, and by 2 in the afternoon start to realise that the brain is no longer working properly and something must be done to warm up!

Evenings are cooling off here now, and just a hint of autumn in the trees, it will be nice for you heading towards spring.

Love to you from Me, Laura, and Ginger the Cat xxx

Peter said...

Thanks Angie

John said...

I just ran across your site and had to mention how beautiful the work you are doing with this kiln.

Peter said...

Hi John,
Welcome to my site. Thank you for your kind comment. I must actually do some more raku work. I was looking at the kiln today thinking that it would be fun to get it going again.