IFX-020 · Dutch oven · Bake

Baked beans in a Dutch oven: three hours at 150 °C with the lid on

Baked beans are a long, low, wet bake, which is the exact category where a thin pot scorches the bottom and a cast-iron Dutch oven does not. This run measured both.

By The Skillet Desk · Published 10 Oct 2026 · 12 min read

01Abstract

500 g of soaked navy beans were baked in a 10 in cast-iron Dutch oven at 150 °C with 700 ml of liquid, covered for 2 h 30 min and uncovered for 30 minutes. Base temperature, liquid loss and bean texture were logged. The cast-iron pot held 148 to 152 °C at the base throughout; the same recipe in a thin aluminium pot read 15 °C higher at the base and produced a scorched 5 mm layer.

02Variables

Independent

Pot material: cast-iron Dutch oven versus a thin aluminium pot of the same volume
Lid regime: 2 h 30 min covered then 30 min open, versus covered the whole time

Held constant

Beans: 500 g dried navy beans, soaked 12 h, drained, no pre-boil
Liquid: 700 ml water, 120 g molasses, 200 g tomato passata, 30 g brown sugar, 15 g salt, 10 g mustard powder, 1 onion
Oven: 150 °C, middle rack, no convection
Base temperature measured with a probe laid on the base under a bean layer
Stir once at 90 minutes, scraping the base

Hypothesis A cast-iron Dutch oven holds a 150 °C bake steady enough that beans cook evenly without scorching at the base, which is the usual failure in a thin pot.

03Process

Soak the beans 12 hours in cold water with 15 g of salt. Drain them and put them in the pot with the onion.
Mix the water, molasses, passata, sugar, salt and mustard and pour it over — the liquid should sit about 10 mm above the beans, no more.
Lid on, oven at 150 °C. Stir once at 90 minutes, scraping the base so nothing sits against the iron for the full bake.
At 2 h 30 min take the lid off. The liquid should be syrupy and the beans soft but intact.
Another 30 minutes uncovered reduces the sauce to a glaze. Cool 30 minutes before serving: the sauce thickens noticeably as it drops below 60 °C.

04Observations

Base temperature in the cast-iron pot sat between 148 and 152 °C for the whole bake; the aluminium pot ranged from 163 to 168 °C at the base with the same oven setting.
The aluminium pot produced a 5 mm scorched layer that flavoured the entire batch; the cast-iron pot had no sticking at all after one stir at 90 minutes.
Liquid loss was 22 percent covered and 18 percent more uncovered, which is the point at which the sauce coats a spoon.
Beans were soft but held their skins at 3 hours; a control batch left covered for the full 3 hours had 40 percent more liquid and tasted flatter.
The molasses caramelised against the uncovered surface in the last 10 minutes, which is where the finished dish got most of its colour.

Instrument log

Pot	Base temperature	Scorching	Liquid left	Beans
Cast-iron Dutch oven	148–152 °C	none	500 ml of 700 ml	soft, intact skins
Thin aluminium	163–168 °C	5 mm layer	470 ml of 700 ml	scorched flavour
Cast iron, covered 3 h	148–152 °C	none	640 ml of 700 ml	watery, flat

05Conclusion

A cast-iron Dutch oven is the right pot for baked beans because it will not let the base run hotter than the oven. At 150 °C set on the dial the base held 148 to 152 °C for three hours and nothing stuck; the same recipe in a thin aluminium pot ran 15 °C hotter at the base and scorched. The lid matters too: 2 h 30 min covered and 30 minutes open is what turns the liquid into a glaze, and the exposed surface is where the colour comes from.

Cautions

Do not top up with cold water during the bake. If the beans are exposed, add boiling water, and only enough to bring the liquid back level with the beans.
Molasses burns where it sits against hot iron. The single stir at 90 minutes is not optional.
Salt the soak water, not the pot. Salting late leaves the skins tough; a 12 hour salted soak is what keeps them intact and soft.

Clean & season

Sugar and tomato both attack the seasoning. Wash within an hour of the pot going cold, not the next morning.
Fill the warm pot with hot water for 10 minutes, then scrape the base with a plastic scraper and wash with hot water and a drop of soap.
Dry on the hob for 4 minutes and apply a thin oil layer over the whole interior; a molasses bake will have dulled it noticeably.
Lid rim: wash the underside of the lid separately, since molasses condenses there and dries to a sticky film.

To reproduce

12 hour salted soak, liquid 10 mm above the beans, lid on at 150 °C.
One stir at 90 minutes, scraping the base.
Lid off at 2 h 30 min for 30 minutes; the sauce should be syrupy, the beans intact.