Sawdust firing

Last night I pulled a handful of the burnished terracotta apples and pears I’ve being making out of the smouldering ashes of my sawdust firing. They were black and shiny, and I was pleased as Punch.  

One or two friends asked me how it’s done, so, at the risk of teaching an awful lot of grandmothers to suck an awful lot of eggs, below is what happened.

Materials (E= Essential, O= Optional)

• 7 apples and pears made of red earthenware clay (E)
• 48 House bricks (E)
• 1 Roll Aluminium Foil (O)
• 1 Big Bag of Sawdust. (E)
• 1 Paving Stone (E)
• Charcoal Briquettes (O)
• Fire lighting kit (E)

Method (Madness?)

1. On a flat surface in the garden I built a square brick chamber – 2 bricks on each side and 6 bricks high. (No mortar or binding materials – just piled bricks)
2. Then lined the inside with ordinary aluminium foil from the kitchen. (My thinking was that it would stop the sawdust from being contaminated by damp from the bricks which had come from the walls of our compost heap. Also, I thought it would stop the sawdust burning too quickly by blocking the drafts blowing through the cracks between the bricks.)
3. A few charcoal briquettes at the bottom then a layer of sawdust into which I embedded by objects. Then I filled the chamber with sawdust to within a brick of the top.
4. Then I lit it and covered it with my paving slab.
5. In theory, at this point I would have walked away and left it to burn nicely. In fact, I discovered I needed to punch a few hols in my aluminium sheets to help the burn.
6. After 5 or 6 hours of smouldering I was able to pull my objects out of the still hot ashes. They were a nice shiny black colour and fired to a hardish biscuit. I wiped them with a piece of kitchen towel dipped in cooking oil and I reckon they should be good for the next six thousand years.  

Conclusions

I was pleased. But then why not? The alternative is having everything blow to smithereens because the fire has got too hot too quickly. I think the aluminium was a good idea, but the holes punched in it were essential in order to allow the sawdust to burn properly. Maybe it wouldn’t be necessary next time as the bricks will be dry. Nonetheless, it will stay there. As for the briquettes at the bottom, which I thought would hold extra heat – I’m not sure they made a difference. As a way of helping to get things started when lighting the top, they worked well.

Next?

I’ve a few more objects to fire, so I’ll be more confident about getting the results I want. I might also be a little less gutless and put in more than one layer. My thinking was that the further the objects were from the heat as the chamber heated up the less likely they would be to blow up – still be good thinking, probably. Time will tell. As for developing other colours, using oxides or low temperature engobes and all that malarkey: right now, I’m minded to keep it simple and carry on – until I run out of sawdust, that is.      

Finally, I was also lucky in that I had all the materials at my disposal.  I doubt whether I’ll be able to get any more sawdust when it runs out in this time of lockdown. So, I guess I just look forward to better times.