In short: A round loaf is shaped in two stages: a preshape followed by a 15–20 minute rest, then a final shape that builds surface tension. That tension is what holds the loaf together and makes it rise upwards instead of spreading across the stone.
Why shape twice
After bulk fermentation the dough is relaxed and holds no shape. The preshape gathers it into a round and gives the gluten strands a direction; the rest releases the tension that builds up; and only the final shape creates the taut surface everything depends on.
You can skip the first stage on very strong dough. On a wet wheat or rye-wheat dough the piece will spread before it ever reaches the proving basket.
Preshaping
Turn the dough onto a lightly floured bench. Draw the edges into the centre around the circle, flip it seam down and round it with your palms — without pressure, so you do not drive out all the gas. Cover and leave for 15–20 minutes.
Final shaping
Turn the piece seam up, flatten it slightly and again gather the edges into the centre, pinching them closed. Flip it seam down and drag it towards you with the edges of your hands, rotating it on the bench: the dough must grip an unfloured surface — that grip is exactly what tightens the top.
Too much flour on the bench is the main reason tension never builds: the piece simply slides.
Checking the tension
A properly shaped piece has a smooth, springy surface with the seam pinched tight underneath. Press it with a finger and the dent fills slowly. A piece that immediately sags and spreads has no tension — reshape it.
What comes next
Place the loaf seam up in a proving basket and retard it cold. Before baking you turn it onto a peel and score it.
Frequently asked questions
How long should the rest between shapings be
15–20 minutes at room temperature. If the dough still resists, give it another ten or the surface will tear during final shaping.
Why does my shaped loaf spread
Either the dough over-fermented and the gluten no longer holds, or there was too much flour on the bench and no tension formed.
Do I need a proper proving basket
No. A colander or bowl lined with linen and dusted with rice flour works — rice flour absorbs less moisture, so the dough does not stick.