December 19, 2015 - 4:54pm
I have a 22" cob oven built on Kiko Denzer's plans. I have been baking in it every weekend for the past six months. I have gotten good results from it but lately my loafs have been blooming out of the side in medium sized bubbles.
The temp of the cob oven doesn't seem to have any effect on the blow outs.
I have been making loaves from Ken Forkish's book, Flour Water Salt Yeast.
I have tired to cut deeper scores into my breads to encourage the loaves to expand correctly but they still blow out the sides. I don't have this problem when I bake in my electric oven with a cast iron pot.
Your dough crusts over too quickly so it can't expand upwards hence the blowout through the sides. Steam helps but very difficult to get steam into some ovens. This is probably why a cast iron pot in your electric oven doesn't have this problem.
I think I am having the same problem. In my case I am fairly certain it is from a miss-balance between the dome temperature and the hearth. My dome has loose perlite insulation but the hearth is insulated with vermiculite/clay slip over bottles. I have no problem with pizza but my breads brown too fast on the top while the bottoms remain pale. My blowouts are more cracks with the top cuts not opening enough.
I am considering either covering the loaf with an inverted dutch over or shielding it with a metal sheet pan. I could also try loading more bread in the oven or cooking something moist to to add stream. Another option I may try is to bake seam-side up alla Forkish to see if that works better.
I could bake in a dutch oven but figure I might as well bake in the electric oven instead.
I have a cob oven from KD book also. I've always damp mopped the floor just before baking anything (besides pizza) to create steam. Also, my door is wood - I soak it all day under water in a bucket and then wrap a wet cloth around it to help it seal, so I get plenty of steam. I also start at an average temp of 600-650 F . I've not had a blow out using that method.