Shaping problem (I think) on Tartine Polenta Bread – a Bread Baking Babes project for January 2018
[Y]ou are talking about a flying crust, aka “the room where the lazy baker sleeps”, it usually comes down to one or two possibilities: how the bread was shaped and whether or not it was docked. […] Docking is just a matter of poking holes in the dough before it goes into the oven. You can use a wooden or metal skewer, or a thin knitting needle. The idea is to provide a path for the escaping steam and other gases during baking so that they aren’t trapped under the crust. Since the crust will dry and harden first, it will contain the steam being generated by the still-raw dough in the inner part of the loaf. That often creates a big bubble at the top of the loaf. The folks at www.breadandbakingscience.com have this to say about rye breads: “When the proofing period is completed, the loaves are washed with corn starch wash or egg wash and a sharp object about the size of a pencil is punched about half way through the loaf about two inches apart the full length of the loaf.”
PMMcCool, The Fresh Loaf, in response to My rye bread gets air pockets
Creating more surface tension on top by pulling it tighter on the bottom while shaping will remedy the problem.
Floydm, The Fresh Loaf, in response to Cavernous Sourdough
In the case of this bread, now that I remember about when I plopped it into the basket after forming it into a boule, I think it was in the shaping that this “Lazy Baker” thing happened. The dough was on the slack side so wasn’t easy to make it taut on the outer surface. (I still think it overrose a tiny bit.)