The parts
The safety valve lets steam out when the pressure climbs too high. A gasket and a filter plate sit under the top chamber. Alfonso Bialetti put the first Moka Express on sale in 1933.
Filling the pot
Water goes in the base, stopping short of the valve. Water over the valve can stop the valve working. Set the basket in and fill it right up with coffee. Level the top, no mound. Do not press it down. Pressed coffee makes the water carve channels through it. Those channels give you a bitter cup. A half-empty basket brews badly, so fill it every time.
| 1-cup | 2-cup | 3-cup | 4-cup | 6-cup | 9-cup | 12-cup | |
|---|---|---|---|---|---|---|---|
| Water, to the valve | 60 ml | 90 ml | 130 ml | 185 ml | 250 ml | 410 ml | 595 ml |
| Coffee, scaled from the 4-cup's 15-17 g | 5-6 g | 7-8 g | 11-12 g | 15-17 g | 20-23 g | 33-38 g | 48-55 g |
| Coffee out | Just under 60 ml | Just under 90 ml | Just under 130 ml | Just under 185 ml | Just under 250 ml | Just under 410 ml | Just under 595 ml |
On the stove
Screw the top on and set the pot on the stove. Bialetti's advice is to take your time. A gurgling sound tells you the coffee has fully risen. That is the moment to take the pot off. If you like, run the base under the cold tap to stop the brewing. Never heat an empty pot.
Hot or cold water
Here the experts disagree. Bialetti says room-temperature water. Stumptown and James Hoffmann say water just off the boil. Their reason: a hot start means less time on the flame. The grounds cook less, they argue, so the coffee is less bitter. Start with hot water. The base is already hot, so hold it with a cloth. Then try the other way once and keep what you like.
Why coffee turns bitter
Bitter moka has a few causes. A grind as fine as espresso makes the coffee bitter. Too much heat does the same. Coffee left on the flame after the gurgle boils and turns ashy. Weak or sour coffee points the other way: grind too coarse, or basket not full. Rinse the pot and dry it fully. Store it with the parts apart.