What 1:15 means
The ratio compares weights, coffee first and water second. Recipes give water in grams because 500 ml of water weighs 500 g. Divide the water weight by 15 to get the coffee weight. A 750 ml press, for example, takes about 50 g. Any size of press uses the same ratio.
| 8 oz | 3-cup | 4-cup | 8-cup | 12-cup | |
|---|---|---|---|---|---|
| Water | 240 ml, 8 oz | 350 ml, 12 oz | 500 ml, 17 oz | 1 L, 34 oz | 1.5 L, 51 oz |
| Coffee at 1 : 15 | 16 g | 23 g | 33 g | 67 g | 100 g |
| Coffee at 1 : 16 | 15 g | 22 g | 31 g | 63 g | 94 g |
| 8 oz mugs | 1 | 1.5 | 2 | 4 | 6 |
Tablespoons or a scale
A level tablespoon holds about 5 to 6 g of coffee. One roaster's recipe works out to about 7 g per tablespoon. Another roaster's rule for brewing without a scale is one tablespoon per 120 ml of water. For a 500 ml press that is about four tablespoons. Four tablespoons can weigh anywhere from 20 to 28 g. A kitchen scale takes the guessing out.
How to brew it
Rinse the press with hot water. Add the grounds and pour in all the water. Set a timer for 4 minutes. Recipes split here. One roaster plunges at once and pours out the whole press. In the other, you break the crust with a spoon and skim the foam. Wait 5 to 8 more minutes. Lower the plunger only to the top of the coffee, then pour gently.
Stronger or milder
More coffee for the same water gives a stronger cup. Roasters' own recipes run from about 1:12 to 1:18. Near 1:12 the coffee is strong; near 1:17 it is light. To adjust, move one point at a time, from 1:15 to 1:14 or 1:16, and taste. Bitter is a different problem. It usually comes from a grind that is too fine.
The sludge at the bottom
A French press filters through a metal mesh. The mesh lets the coffee oils through, so the cup feels heavier in the mouth. It also lets tiny particles through, and those settle at the bottom of your cup. A coarser, even grind from a burr grinder leaves fewer of them. Once you have poured, move any leftovers to a jug. Coffee sitting on the grounds keeps brewing.