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Sunday, June 13, 2010

The Barrel Firing Test

Just a quick warning: This post is going to be quite long as it is a start to finish description of the barrel firing I've been planning. But I remembered to take lots of photos, so you can just scroll down if you get bored with my inane drivelling!
OK, where to begin?

First, I laid out everything:

These first 2 photos show the pots and some little figurines to fire. The box contains: wood shavings (basically the pet bedding I use to line my bird's nest boxes), iron oxide, manganese dioxide, copper oxide and salt. Then I had some newspapers and a load of wood offcuts which I chopped up, a few old chilli plants from last years crop (I've just taken down the old greenhouse!). The garden incinerator (dustbin with holes in it) I was given by my next door neighbour, as well as some duct pipe I'll come back to shortly.

The first layer. Screwed up tubes of newspaper with wood and shavings on top. Then the pot, more shavings and a sprinkle of oxides and salt.


...and repeat.

The only pic I forgot to take was the final pyramid of newspaper, kindling and wood on top.
This next part is where I went wrong. I thought it would be a good idea to create an up-draft kiln design, so I attached ducting to the stubbly outlet on the dustbin lid. I also lit the barrel from the top and bottom, I should have only lit the top and not put the lid on as you'll see.

Here's the bin just after lighting. The smoke drifted everywhere as there was only a gentle breeze. I'm surprised the fire brigade didn't turn up! 
After a few minutes it began to burn properly and the smoke died down. My neighbour, who had joined me for this experience, mentioned how hot it was getting. I replied that if it got really hot a flame might shoot out of the top of the chimney, like a kiln in reduction. He laughed sceptically...two minutes later:

I had a jet engine in the garden! The heat was amazing, in fact too much so. The pots began to glow red! All this happened within the first twenty minutes or so, which as you'll see didn't do the pots much good. I estimate they went from cool to between 900 and 1100 degrees C in that time; and although my clay is groggy it can only take so much thermal shock.
As an aside: This design would be very effective lined with ceramic fibre as a cheap up-draft kiln. I might look into this at another time. However next time I do a barrel firing the lid will be removed, or (to take the smoke away) propped a couple of inches off the top of the bin.

So, this morning I went out (after plucking up the courage) to face what I thought would be a bin full of exploded pots. To my surprise this was what I saw. Some had survived. I took them out and brushed them off and was left with the following:

These were the pots which were broken or cracked beyond rescue.

The pic. above shows the pots which were cracked, but not to any great extent. After all this was a test so I needed as many as possible for the next steps.

And so these few things are the only un-cracked remainder. It may sound strange, but I wasn't disappointed. This was a test after all, if everything had emerged perfectly what would I have learnt?
So, things to do differently next time: 1) Don't light the fire from the bottom only light the top. 2) Don't put the lid on unless I want a roaring inferno. 3) Wrap the pots in newspaper with the oxides and wood shavings together, that way I should get the effects all the way around the pots more effectively.

So next I washed the pots. In case you're wondering: with washing up liquid in a bowl or warm water. Some people say you should wipe the pots with a wet cloth but I thought it made more sense to just treat them as normal pots. It worked fine so here's the resulting pots drying out:

So next I tackled the waxing. I'm a lazy man as you know, I could have gone out and bought some soft wax but instead I reached for the shoe cleaning kit and grabbed some neutral shoe polish. My thinking was: "It's a wax polish, what difference can it make?". The answer was...none. Here is one of the pots at the three stages:
1st: Washed but apart from that untouched:

2nd: With wax applied but not polished:

3rd: Polished with a soft cloth:

I am genuinely surprised by the results. I wish you could see the effects properly, there are ox-blood reds and soft yellows as well as the black you can see. I will be buying some soft wax as it would be easier to apply a slightly thicker, more even coat.
This is definitely how I plan to work from now on. Although there is an intrinsic risk in barrel firing the results, too me, are worth it. I can't wait for the chance to try it on my sculpted pots, although I think I'll start with the small bait ball and work my way up! I don't think I'll risk cramming the bin full again, unless I do some small repeat thrown pots. I suppose I could do that and not bisc fire them first. Leave the lid on the bin and see if they fire properly in the inferno...hmmm?
The following photo is of all the finished pots. It is a large pic so you should be able to click it to see it full size (I hope).
Thanks for visiting, here's hoping I haven't bored you too much. Any suggestions or tips are always gratefully received.


  1. i'm so far behind on reading my blogs! this is great mark, i love the jet engine shot lol. i'm going to have to give this a try sometime. your pots turned out great!

  2. I didn't find any of this boring, just inspirational and so interesting. What an atmosphere of intensity of what the outcome would be. wow.
    I am a beginner potter and have weekly lessons and now have my own wheel. discovering new things all the time. this morning I began with terracotta and had watched your video of making small bowls off the mound (is that right). anyway I had a go today to the delight of my tutor. So thank you so much for your video it helped me to think about how I was doing it. now I have to find time to watch some of your others. Gai

  3. Excellent Mark, the pots look fantastic, I'll show my evening class this post, so they get an Idea as to what can be achieved.
    Looks scary at points.

  4. thanx for your grat post , i just built a downdraft barrel kiln, as per directions from book, alternative kilns and firing techniques , with downdraft chimney on bottom of 55 gal drum , did a test fire (no pottery) and works just as outlined in book. you can check out pics of kiln on my blog
    love the picture of the chiney looking like a rocket ship

  5. Thanks for sharing so much detail. I've started experimenting firing greenware with sawdust on a small scale in a stacked-brick kiln, three bricks high. They result is a soft product that can be broken by hand. I'm now going to try wood and sawdust in a drum like you did. Have you fired greenware in this way yet?


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