Steam in the first ten minutes decides how high the loaf can go

These are listed in the order worth acting on, which with oven steam during the early bake is not the order they are usually presented in.

Why the crust setting early is a problem

In a dry oven the loaf surface dries out fast, and dried dough stiffens into a shell that resists further expansion. Inside, the gas is still heating and expanding, and the trapped water is turning to steam and pushing outward.

If the shell has already set, that pressure either bursts the loaf somewhere unplanned or simply has nowhere to go. Steam in the oven keeps the surface moist and elastic for those first critical minutes, so it stretches instead of cracking. The window is short: most of the useful expansion happens in the first ten to twelve minutes.

What steam does to the crust itself

A moist surface gelatinises the starch at the outside of the loaf, which later dries into the thin, glossy sheen good bread has. That gelatinised layer also browns more readily, because the starch is being broken down into sugars available for browning reactions.

Once the crumb sets, without steam you get a matte, thick, pale crust, and the loaf usually needs longer in the oven to colour at all. Too much steam for too long gives a leathery, tough crust, since the surface never gets a chance to dry and crisp. The sequence matters as much as the amount: wet first, dry afterwards.

Getting steam in a home oven

Domestic ovens vent constantly and are not designed to hold moisture, so anything you add escapes quickly. A preheated cast iron tray on the oven floor with a cup of boiling water poured onto it produces a burst that lasts a few minutes. Lava rocks or a bed of steel nuts in a tray hold heat better and flash more water into steam than a bare pan does.

By the second rise, spraying the oven walls does very little, because a fine mist has no thermal mass and the water evaporates and vents. Whatever you use, close the door immediately and do not open it during the steam phase.

The covered pot approach

Baking inside a preheated cast iron pot with the lid on traps the water the loaf itself gives off, which is more than enough. This is the most reliable method in a home kitchen because it does not depend on the oven holding anything. Remove the lid after fifteen to twenty minutes so the crust can dry, darken and crisp for the remainder of the bake.

The dough tells you first: the pot needs a proper preheat, typically thirty to forty five minutes at 230C, or the base of the loaf will be pale. Any heavy lidded vessel works; there is nothing special about the enamel or the brand.

Temperatures around the steam phase

A common pattern is 230 to 250C with steam for the first fifteen minutes, then 210 to 220C dry for another twenty five to thirty. The high start drives the initial expansion and the drop prevents the crust burning while the centre finishes. Enriched doughs with sugar and milk brown far faster, so they usually start lower, around 180 to 190C, and need no steam at all.

At oven temperature, check the internal temperature rather than the clock, aiming for around 93 to 99C for a lean loaf. Ovens differ enough that these figures are starting points to calibrate against, not fixed instructions.

Proving times are written for a warm kitchen, and yours may not be one.

Diagnosing a steam problem

A loaf with poor spring, a dull thick crust and a tight crumb near the top has usually been baked dry. A burst along the side rather than the score points the same way, since the crust set before the loaf finished expanding. Conversely a pale, soft, slightly wrinkled crust means the steam stayed too long and the surface never dried.

By the second rise, change only the steam variable across two bakes and the answer becomes obvious very quickly. Most home ovens err heavily on the dry side, so start by adding rather than removing.

Everything above, in order of what to do first

1. Why the crust setting early is a problem. In a dry oven the loaf surface dries out fast, and dried dough stiffens into a shell that resists further expansion.
2. What steam does to the crust itself. A moist surface gelatinises the starch at the outside of the loaf, which later dries into the thin, glossy sheen good bread has.
3. Getting steam in a home oven. Domestic ovens vent constantly and are not designed to hold moisture, so anything you add escapes quickly.
4. The covered pot approach. Baking inside a preheated cast iron pot with the lid on traps the water the loaf itself gives off, which is more than enough.
5. Temperatures around the steam phase. A common pattern is 230 to 250C with steam for the first fifteen minutes, then 210 to 220C dry for another twenty five to thirty.
6. Diagnosing a steam problem. A loaf with poor spring, a dull thick crust and a tight crumb near the top has usually been baked dry.

The takeaway

Wet for the first quarter of the bake, dry for the rest, and the loaf will tell you it worked.

Bake it badly once on purpose. The failure teaches more than the photograph.