Inside the Ferry Building, in the heart of San Francisco, Blue Bottle Coffee is brewing up some of the best coffee in the city. Wafts of the stuff stream into our newest Pressed Juicery location next door. We’re feeling pretty lucky to have such great California-based shops as neighbors (check out the others here) and we wanted to share a few insights from each of them about the gorgeous local products that each of these artisans are creating. Here is a little direct access to Blue Bottle’s fresh brew: founders James and Caitlin Freeman are sharing the science behind the perfect pour-over!

The two indispensable tools for making better pour-over coffee are a gram scale and a swan-necked kettle. Using a swan-necked kettle will help the accuracy of your pour and, hence, improve the consistency of your extraction. Some people might rebel at paying $50 for a kettle, but how many people have a pizza stone they never use or an ice cream maker that lives in the back of a kitchen cabinet? If you buy a gram scale and kettle, you’ll use them every day, and you’ll drink better coffee almost immediately. Every morning, your first thoughts will coalesce around making something wonderful. Your friends will beg you to make them coffee and share your mastery. It’s money well spent.

A coffee mug usually holds around 10 fluid ounces. We’re going to call that 300 milliliters. Conveniently, 1 milliliter of water (a measurement of volume) equals 1 gram (a measurement of weight). So, armed with this secret knowledge, you can proceed knowing that pouring on a tared (zeroed) gram scale tells you not only the weight of the water, but the volume of water you’ve poured. If you employ a timer as well, you’ll have relevant information about flow rate and extraction time. And if you add a thermometer, you can also collect data about temperature of extraction. Data points, before breakfast!

  • Pour-Over Coffee
    Makes 1 serving, about 10 fl oz (300 ml)

  • What You'll Need:

    About 2 1/2 cups (20 fl oz or 590 ml) good-quality water
    Swan-necked kettle
    Gram scale
    20 to 35 grams (0.7 to 1.2 oz) coffee beans
    Coffee grinder
    Thermocouple or other thermometer
    Ceramic coffee dripper
    Coffee cup
    Paper filter (kenaf or bamboo-based paper is best)

  • Directions:

    You will need 10 fl ozs (300 ml) of good-quality water for your coffee, so put double that amount in a kettle or other vessel used only for heating water. Why double? Because you’ll use some of the water to preheat the dripper and cup. Put the kettle over high heat.

    While the water is heating, weigh out the coffee; the amount depends on the brewing ratio you’ll use, from 20 grams for a 15-to-1 ratio, to 30 grams for a 10-to-1 ratio. Grind the coffee finely enough that it forms a clump when pressed between your thumb and forefinger; it should feel soft but still a bit gritty. Grind size and evenness is one of the few immeasurable factors – at least at home. At the roastery, we measure particle size and distribution of the powdery particles, called fines, when evaluating grinders, but at home, intuition rules. Change it up and try different settings to find one you like.

    When the water comes to a boil, pour it into the swan-necked kettle, then let it sit until the temperature is between 185°F and 205°F. Warm the ceramic dripper and cup with some of the remaining hot water.

    Put the filter in the dripper and pour in the ground coffee. The coffee should naturally take the shape of a gentle mound. Place your now-empty but warm cup on your gram scale, set the coffee-filled ceramic dripper on top, and tare (or zero) the scale.

    Gently and slowly drizzle a small amount of hot water in the center of the mound of coffee, away from the sides of the filter, and making a circle about the size of a quarter. The goal is to pour in just enough water so that the coffee will absorb all of it without any liquid dripping into your cup. Coffee generally holds double its weight in water. This is easy to check if your cup, dripper, and coffee assemblage is set up on your gram scale. For example, if you have 35 grams (1.2 oz) of ground coffee in the filter and have tared the scale, add water until the scale reads 70 grams (2.5 oz). Voilà! Pouring in water in such a way that none comes out is a skill. The better you are at soaking the coffee mass evenly, then the more water it will absorb. Can you pour twice the weight of the ground coffee amount without any dripping? 1.75 times? 2.25 times?

    You can take satisfaction from doing this well, but it isn’t just a geeky fine point; it has an impact on the coffee you brew. It facilitates blooming, the process in which hot water causes the coffee to expand outward in a fascinating way. Allow it to bloom for 30 to 45 seconds, or up to 60 seconds for coffee roasted over 1 week previously. A slightly longer blooming time can add a lot of depth and vitality to older coffee.

    Pour in more water, once again pouring slowly in a small circular pattern in the middle of the filter. A light-brown cap should rise; at Blue Bottle we call it “the mushroom.” The pace of your pour should be approximately equivalent to the speed at which coffee is flowing out of the filter into your cup. In other words, the level of the mixture of coffee and water in the filter should neither rise or fall. Furthermore, the level of the mushroom should be maintained at just about two-thirds up the sides of the cone. Aim for somewhere between 1 and 2 milliliters (1/4 to 1/2 teaspoon) of water per second. There are 15 milliliters in 1 tablespoon, so that’s about 1 tablespoon per 7 to 15 seconds.

    Remember, extraction rate is determined by many variables beyond how fast you pour: amount of coffee, grind size, percentage of fines, and water temperature. So the pour contributes to the speed of the extraction, but doesn’t define it. Don’t be frustrated if you can’t pour slowly and steadily right away. It’s a skill. Just keep practicing.

    Once you’ve poured the desired amount of water, remove the dripper. The coffee will taste better if you don’t let all the water flow through the filter into the cup. At the end of the brewing cycle, you are starting to extract some undesirable compounds from the coffee; keeping those away from the coffee you are drinking will produce a more delicious product.

    Drink your coffee, and marvel at your dedication and skill. Repeat as needed.

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