How Does Coffee Extraction Work in a French Press?

French press coffee depends on immersion extraction: grounds and hot water steep together, then a metal plunger filter separates them. Because there is no paper filter, oils and fine particles stay in the cup, giving a heavier body. Getting a repeatable result comes down to four variables: the coffee-to-water ratio, how coarse the grind is, water temperature, and steeping time.

The method traces back to 19th-century France, where a piston-filter device was patented in 1852 and sold as the French Press. Medium or medium-dark roasts suit it well, since immersion draws out sweetness and body. Beyond brewing, the same pot can be used for cupping, tea, frothing milk, and iced coffee, and it disassembles for straightforward cleaning.

Since the French Press was invented in 19th-century France, its simple structure and immersion extraction method have made it a daily choice for many coffee lovers. But to consistently produce a good cup with it, there are finer points to how you choose the coffee grounds, how coarse to grind, how hot the water should be, and how long to steep. This article draws on Front Street's hands-on experience to lay out the French Press's coffee-to-water ratio, grind size, water temperature, and timing parameters, and extends to uses like cupping, brewing tea, and frothing milk, plus a French Press iced coffee extraction recipe and disassembly and cleaning method, to help you use this simple device more thoroughly.

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The French Press originated in 19th-century France and is written in English as French Press; in Chinese it is also often called "French-style press pot." There is no definitive year for its specific birth, but in 1852 the Frenchmen Mayer and Delforge founded the "Smith" company, applied for a patent for a piston-filter coffee device, and named it "French Press," which is usually regarded as the starting point of the French Press's commercialization.

The French Press's design is simple and convenient The so-called simplicity is reflected in three aspects: structure, principle, and operation. The whole French Press consists of a heat-resistant glass carafe and a metal filter with a plunger rod. When brewing, you only need to put coffee grounds and hot water into the glass container to steep, then separate the coffee grounds through the metal filter with the plunger rod, and you get a relatively clean cup of coffee. In the entire process, the only actions that need to be done manually are three steps: add grounds, add water, press the plunger.

Key points for brewing a pot of coffee with a French Press

Because the French Press is an immersion extraction, Front Street believes it is better suited to pairing with medium-roast or medium-dark-roast coffee beans. If you want to drink French Press coffee with floral and fruity notes, you can try Front Street Strawberry Candy Coffee, Front Street Mozart Coffee, Front Street Sidra Coffee; if you prefer rich nutty flavors, then Front Street Queen's Estate, Front Street Golden Mandheling, and Front Street Huila are recommended. All the above coffee beans can be purchased at Front Street's Tmall flagship store or Front Street's Taobao store, and orders are shipped within 24 hours after placing them.

The French Press mainly relies on immersion to complete extraction. At a fixed capacity, a set amount of water will evenly dissolve the soluble substances in the coffee grounds. During extraction, time is the most critical influencing factor: the longer the immersion, the more substances are extracted, until saturation or until it enters a state where further extraction is more difficult—that is, the longer it steeps, the stronger the taste.

Therefore, the first step is to determine the coffee-to-water ratio. Front Street usually recommends a coffee-to-water ratio of 1:15 to 1:16. This range has a high tolerance for error, and most coffees can show a good mouthfeel and flavor at this ratio.

Next, determine the grind size. Front Street recommends using a coarser grind for the French Press, because the French Press relies on a metal filter to filter, and the mesh gaps are visible to the naked eye; choosing a coarser grind is also for smoother filtering. Beans of different roast levels also differ in grind size: measured by the passing rate of a No. 20 standard sieve, medium-light roasted coffee beans can use a finer grind (passing rate 72-75%), while medium-dark roasted coffee beans should be ground coarser (passing rate 68-71%).

Then there is the water temperature. Because the French Press uses immersion extraction, the coffee grounds and water are relatively still during the process, so the water temperature is chosen to be a bit higher. For the same bean, the brewing water temperature for a French Press is 2-3°C higher than for pour-over. For brewing medium-light roasted coffee, 91-94°C is recommended; for brewing medium-dark roasted coffee, 88-91°C is recommended.

Finally, there is the immersion time. As mentioned earlier, time is crucial for the French Press. After many brewing comparisons, Front Street believes that most coffee beans have the best taste and mouthfeel when steeped for about 4 minutes according to Front Street's recommended parameters. You can also use this set of parameters as a foundation and develop your own preferred brewing method.

The operation process is actually very convenient. Taking 15g of coffee grounds as an example, pour the ground coffee into the pot, add 225-240ml of hot water, pull up the plunger rod, cover with the lid, and let it sit for 4 minutes. Then slowly press down the plunger rod, letting the metal filter stop at about 1/4 of the carafe, to avoid fine grounds at the bottom surging upward.

Although the French Press is simple, its functions go beyond brewing coffee

It can also serve as a cupping tool

The process of making coffee with a French Press is quite similar to cupping—both complete extraction through static immersion—so many people use it to test the quality of coffee beans. The French Press brewing method recommended by James Hoffmann, author of The World Atlas of Coffee, is exactly the same as the cupping method.

It can also be used to brew tea

The French Press combines immersion and filtration into one, with a simple structure; it can brew coffee, and of course it can also be used to brew black tea, and it is equally convenient to use. If you pay attention, you will find that the tea brewers sold on the market are very similar in construction to the French Press.

It can even froth milk

The French Press can also be used to froth milk. If you want to make cold milk foam, you need a manual milk frother—in fact, the construction of a manual milk frother is very similar to that of a French Press; pumping the plunger rod of the French Press can also create milk foam just like a milk frother.

Some people ask: Can a French Press make iced coffee?

Front Street was surprised at first, but since a friend raised this question, we will share with everyone the French Press iced coffee recipe we summarized after many attempts.

Concept

The French Press is based on the principle of immersion extraction. With the same beans, hot coffee made in a French Press is usually more balanced and has a fuller mouthfeel than pour-over. Therefore, you can borrow the idea of Japanese-style iced pour-over to make French Press iced coffee: use less hot water to steep the coffee, extract a concentrated hot coffee liquid, then pour it into ice cubes to dilute and cool it, forming iced coffee.

Considering that ice needs to be added to dilute the coffee concentration, it is not suitable to make iced coffee with light-roast coffee that has higher acidity. On the one hand, dilution will make the mouthfeel thin; on the other hand, steeping light-roast coffee with acidity very easily produces undesirable flavors such as almond and peanut skin. In the end, Front Street chose Honduras Sherry coffee beans, which have a mellow mouthfeel and rich vanilla and sherry aromas, making them very suitable for immersion extraction.

Extraction recipe

①Preparation stage: prepare a French Press, electronic scale, glass cup, hot water, and ice cubes. Use 15 grams of coffee grounds. To obtain a more concentrated hot coffee liquid, the ratio of coffee grounds to hot water is 1:8, and the water temperature is 94°C. As for grind size, because the French Press uses a metal filter to filter, it is not recommended to increase the extraction yield by adjusting to a finer grind. Use a medium-coarse grind (passing rate 65% on a No. 20 standard sieve).

②After grinding the coffee, pour it into the French Press, add 120 grams of hot water (start timing at the same time), and pour the water directly into the center.

③After 30 seconds, stir the coffee grounds layer with a stirring stick to increase the extraction yield, forming three layers: coffee liquid, coffee grounds, and coffee foam.

④Cover the French Press lid and wait until 3 minutes; during this time, you can put 105 grams of ice cubes into the glass cup.

⑤After 3 minutes, slowly press down the plunger rod. Let it sit for 1 minute to allow the coffee grounds to settle.

⑥At the 4th minute, pick up the French Press and pour the coffee liquid into the glass cup containing ice cubes.

In this way, a cup of iced coffee made with a French Press is complete. Because it is filtered with a metal filter, the surface still retains good coffee oils, and the vanilla flavor of the Sherry coffee beans can also be presented well; it is refreshing without losing mellowness.

So, how do you disassemble and clean a French Press?

As mentioned earlier, the French Press uses a metal filter design and will retain coffee oils. Although it is environmentally friendly and allows you to enjoy a pot of coffee without consuming extra filter paper, it also means the French Press needs to be cleaned more carefully. If you are lazy and neglect it, the coffee oils left on the pot will affect the taste of the next cup of coffee.

The construction of the French Press is not complicated; it mainly consists of a glass carafe, a metal filter, and a plunger rod. What mainly needs to be disassembled is the metal filter part, because it is made up of multiple layers, and it is difficult to clean all the internal parts thoroughly without taking it apart. First, grip the head of the plunger rod tightly with one hand, and with the other hand twist and loosen the metal filter part. Then clean the remaining components, drain the water, and reassemble.

The above content is compiled by CoffeeHunters, a coffee news website.