Hi all, I built a cob oven recently, and when I removed the sand from inside I found some fairly substantial cracks inside (around 1cm wide, running for at least 40-50 cm each), which luckily do not appear to be structural. I have not yet fired the oven, what I would like to know is whether I should patch the cracks before firing, or just leave them be? Any assistance given would be much appreciated!
