Why does bread have big holes -- or none at all?
An open, irregular crumb isn't luck, and a tight, uniform crumb isn't a mistake -- both are the predictable result of the same handful of levers, set differently on purpose.
The kitchen answer
Big, irregular holes come from wet, well-developed dough that was fermented a long time and shaped gently. A tight, even crumb comes from the opposite choices at every one of those points -- neither is right or wrong, they're different targets.
What's actually happening
Hydration sets how much gluten forms and how easily gas bubbles can expand through it -- wetter dough has a looser, more extensible network that lets bubbles merge and grow unevenly. Fermentation time matters just as much: a long, slow rise gives gas bubbles time to merge into large, irregular pockets, while a short rise produces many small, evenly distributed bubbles instead.
Shaping is the final lever, and it can undo everything else: gentle shaping preserves the large bubble structure that hydration and fermentation built, while firm shaping and degassing pop those larger bubbles back down into a fine, even crumb -- which is exactly why a sandwich loaf (degassed and shaped tightly) and a ciabatta (barely shaped at all) can come from doughs that started out fairly similar.
What does that mean for your recipe
Chasing an open, holey crumb by only increasing hydration and skipping the other two levers often disappoints -- a wet dough that's shaped firmly, or baked after only a short rise, will still come out relatively tight, because hydration alone didn't get the chance to do its part. All three levers need to point the same direction for the effect to actually show up in the final loaf.
What can go wrong
- High-hydration dough that still bakes tight: often over-handled or degassed during shaping, undoing the open structure the hydration and fermentation had built.
- Sandwich loaf with unwanted large holes: under-shaped or under-degassed for a format that's meant to be uniform.
- Dense crumb despite long fermentation: under-hydrated or under-developed gluten limiting how much the bubbles can actually expand, regardless of time given.
- Inconsistent results between loaves: shaping pressure is the hardest of the three levers to apply consistently by hand, and small differences there show up clearly in the final crumb.
Try it yourself
Same dough, two shaping approaches:
- Make one batch of high-hydration, well-fermented dough.
- Divide it in two.
- Shape one piece as gently as possible; degas and shape the other firmly, like a sandwich loaf.
Watch for: dramatically different crumb structure from identical dough, purely from the shaping step -- direct proof that shaping is a real, independent lever, not just a cosmetic final step.
Go deeper
This is the practical, controllable side of the same system covered in why over-proofed dough collapses -- both are about how far gluten's elastic network gets stretched by expanding gas before baking locks the structure in place. Open crumb is that stretching pushed close to its limit, on purpose and under control; over-proofing is the same stretching pushed past it.