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Hairline cracks inside cob oven

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  • Hairline cracks inside cob oven

    Hi guys, I cured my brand new cob oven for the past 6 days. Today I decided to try and burn off the black carbon inside my dome but noticed some long hairline cracks running inside the dome as shown in the enclosed images. I decided to hold fire as I wasn’t sure whether further increasing the temperature would create further issues. Do you believe there is cause for concern?

  • #2
    You don’t say how long you left your oven to dry between completing it and the first fire. But, as a rule of thumb, depending on air temperature, movement and humidity, it takes around a week per inch of thickness to dry sculptural clay work and a cob oven much the same. Even when dry the firing must proceed slowly or cracking and at worst steam spalling result.
    Kindled with zeal and fired with passion.


    • #3
      I let it dry out for almost 3 weeks. I suspect the last fire was a bit on edge and led to most of these cracks. Like I said they are very narrow cracks and will probably try to patch them up after I clean out the black carbon.