The Fresh Loaf

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Bottom blowout on baking stone

chocoberrie's picture

Bottom blowout on baking stone

Hello everyone! 

I used my baking stone for baking bread for the first time today, for a recipe that turned out lovely in my Dutch oven. Unfortunately, these two loaves came out super wonky - the dreaded “bottom blowout!” (The boule is below; the batard is the thumbnail of this post.)

Blowout boule

I didn’t know whether to laugh or cry when I took the first loaf out of the oven. XD

After some searching around the forum posts, I think that these two loaves were probably taken out of bulk fermentation too soon, and the shaping wasn’t so good either (especially with the batard). 

Here’s what I did (the recipe is the Simple Sourdough from The Perfect Loaf, though I decided to make a levain):

5-hour levain (in my Sourdough Home at 74 degrees for about 6.5 hours to let it ripen more):

  • 53 g starter
  • 106 g white flour (50/50 AP/bread flour blend)
  • 106 g water (78 F)

 Autolyse (30 min):

  • 153 g levain
  • 767 g bread flour
  • 85 g whole wheat flour
  • 537 g water (86 F to reach a desired dough temp of 78 F)

Final mix: 

  • 43 g water
  • 15 g fine sea salt

Bulk Fermentation (4 hours at 76 degrees in the B&T proofer box):

  • I did 3 stretch-and-folds, one every 30 minutes, until the last 2 hours.
  • After taking the dough out of the proofer box, I divided and pre shaped, and let it sit on the counter for 35 minutes.
  • During the final shaping, I struggled to make clean seams on both loaves. The batard shaping was definitely a bit messier than I would have liked.
  • I put the loaves into bannetons and then into the fridge for overnight proofing (approx. 10 hours).


  • Preheat the oven for 30 minutes to 450 F with the baking stone in the middle of the oven and a roasting pan on the lower rack right above the bottom heating element. (My oven has a top heating element as well, and I can’t control either one.)
  • I scored each loaf right out of the fridge. As soon as the first loaf was scored, it went into the oven. The second loaf (the boule) stayed in the fridge until the first one (the batard) was done.
  • I sprayed each loaf before sliding them onto the baking stone (on parchment paper). I baked each one individually.
  • As soon as the loaf went in, I put 5-6 ice cubes into the roasting pan for steam. The roasting pan was underneath the baking stone.
  • I left the steam pan in the oven for the first 15 minutes for each loaf, then took it out.

Possible causes for the “bottom blowout”:

  • Bulk fermentation could have gone for 15-30 minutes more.
  • Poke test - the dough sprang back a little bit after I took it out of the fridge, but not completely.
  • My previous loaves have been overproofed after being in the fridge for up to 19 hours, so I erred on the side of caution and took these two out of the fridge around 10 hours.

I made this same recipe on Friday night but halved to make only one loaf, and it came out beautifully in my Dutch oven. (I did let it bulk ferment for 15 minutes longer until I saw more air bubbles and the dough felt fluffy and jiggled a bit in the bowl.) Here’s the crumb of this loaf:

Dutch oven loaf

What do you guys think? Are the two aforementioned loaves underproofed? How do you guys bake directly on a baking stone without this happening?

tpassin's picture

I've only seen this kind of thing once.  One of my loaves didn't slide far enough onto the baking stone and sagged over the near edge.  After it had baked for I forget but maybe 10 minutes - the loaf looked fully formed and risen -  I tried to move the loaf fully onto the stone (I used hot pads).  But the dough stuck and tore, and the interior oozed out like a very thick liquid.

It looked something like your picture.

Since it seems unlikely that you wouldn't have noticed something like that, I'm thinking maybe a major seam didn't get sealed strongly enough.


chocoberrie's picture

I did use parchment paper underneath to prevent sticking, but I do see what you mean about the bottom seam. I tried to seal it up as neatly as I could, but it was tricky. I need more practice!

Abe's picture

The crust formed before the oven spring had finished. The gas had to escape somewhere which so it took the easiest route which would now be through the side close to the base of the loaf. 

chocoberrie's picture

Ohhh, that makes sense. I think I'm just going to have to stick to my Dutch oven, unless I can figure out how to cover the loaf while it's on the baking stone with something tall enough... Hmmmm...

pmccool's picture

And there's your answer.  The loaves that blew out weren't adequately fermented.  The loaf that was adequately fermented didn't blow out.

There's also the possibility that the blowout loaves could have been scored more aggressively. 

My money would be on managing fermentation, both bulk and final, so that the loaves have good (but not explosive) oven spring while baking.


chocoberrie's picture

Yep, I'll definitely be trying the recipe again and give the loaves longer bulk time. I'm also going to try the towel steaming method, and I'll shield the bread from the top heating element to keep the crust from setting too soon. Thanks for your feedback Paul!