Clay/Cob First Few Firings/Curing

[Gef]

I am a bit uncertain about my terminology. I assume my first few firings are for the purpose of curing, and that this means I am drying out my clay.

This process is more of a challenge than I expected. I had some excellent advice from DavidS here (Homemade Clay Pizza Oven (Mk I)).

I used briquettes (heat beads as we call them in Oz) today, about a kilo. I think all was well until I threw on a small log to increase the temperatue. One of my hairline cracks ran to meet the edge of the dome in three places. I couldn't get a match into the gap, but hairline is certainly an understatement. I am happy to patch it up later.

I am wondering about other people's experience. Does anyone else on the forum have a clay WFO with no flue? Can you tell me about your experience of curing?

...Gef

[david s]

You'll need to burn way more than a kilo of heat beads to dry that thing. Try to avoid direct flame on the inner dome. Assuming the weather is dry, allowing a few days to let the moisture from the middle of the walls migrate out a bit more before firing again would help. I'd be burning about 20 Kg of beads before looking at direct flame. Don't forget you can use the heat to cook stuff. Have you or a neighbour got a chook you can cook? you will find it will come out delightfully moist.

[Gef]

Thank-you David. I appreciate your advice, and can see the effect of not following it - in the form of a large crack. I am progressing nonetheless, and will do some patching down the track. No sign of cracking inside, I guess due to the crack on the outside layer relieving pressure.

...Geoff