the home barista field guide

Processing Coffee grows as a cherry. The bean you brew is the seed. Processing is everything that happens between picking the cherry and getting a dry green bean ready to ship — and it's the second-biggest flavor decision after origin. Two coffees from the same farm processed differently will taste like two coffees. 5 min How coffee is roasted Roasting is the chemistry that turns a green seed into something that tastes like coffee. A green bean is dense, vegetal, and sour — undrinkable in any meaningful sense. Heat applied for the right amount of time transforms it into the aromatic, brown, brewable thing on the shelf. Almost everything you taste in a finished cup was either created or shaped during the eight to fifteen minutes the bean spent inside a roaster. 8 min Roast levels Roasting is heat applied for time. Green beans go in tasteless and dense; out comes coffee. Where the roaster stops the process — measured in colour, time, and internal bean temperature — decides how much origin character survives versus how much "roasted coffee" character takes over. 4 min Freshness and storage The roast date on the bag is the most useful number printed on it. A bag's flavour changes more in its first month than at any other point in its life. Buying recent and storing it right is the cheapest upgrade you can make to your coffee. 5 min Origin Where the coffee grew shapes the cup more than almost anything else. Soil, altitude, climate, and varietal interact for the years the tree spends in the ground. Once the cherry is picked, the rest of the chain (processing, roast, brew) only modifies what's already there. You can't put fruit into a coffee that wasn't grown for it. 5 min

Filter coffee, end to end Filter coffee is hot water flowing *through* a bed of grounds, with a filter catching the spent coffee. It's the most common home brewing approach worldwide — and the one with the biggest gap between a mediocre cup and an excellent one, all without a pressurised machine. This page is the whole arc: what you need, what each number does, how the technique runs, and how to tell if the cup is good. 8 min Grind size The first lever, and the biggest one. Before water temperature, before ratio, before pour technique — the grind decides how fast water can pull flavor out of the bed. Move it and everything else follows. 4 min Water temperature Hotter water pulls flavor faster. That's the whole rule. Everything else is matching the temperature to what you have in the bag. 3 min Coffee to water A ratio is two numbers: how much coffee, how much water. Read 1:16 as one gram of coffee for every sixteen grams of water. Lower numbers mean stronger coffee. 4 min The bloom Fresh coffee holds CO₂ from roasting. If you pour the full brew at once, that gas pushes water away and the extraction goes patchy. The bloom is a small first pour that lets the gas vent before the real work starts. 4 min Pour technique How the water enters the bed is half the recipe. Same coffee, same grind, same ratio — three pour techniques give you three different cups. 3 min Stages of a brew Every pour-over is four phases, in the same order, every time. Knowing what each phase does is the difference between following a recipe and reading what's happening in front of you. 3 min Brewer families Brewers split into three families by how water meets coffee. Each family has a character. Knowing which family you're using tells you what kind of cup to expect — and which mistakes are easy to make. 4 min Read the cup Your tongue is the most accurate diagnostic tool you'll ever own. The hard part isn't tasting — it's naming what you taste, and knowing which lever to move next. 5 min

Filter vs immersion Every brewing device sits on one side of a single line. Filter brewers (V60, Kalita, Chemex, Origami) move water *through* the bed. Immersion brewers (French press, Clever, cold brew) let water *sit* with the grounds and then drain. AeroPress is a hybrid that gives you both, depending on how you use it. 3 min V60 Hario's conical brewer is the most copied design in modern coffee, and for good reason: a 60° cone, deep ribs, and one big hole add up to a brewer that doesn't restrict flow at all. The grounds are what hold the water back, not the device. That makes the grind and your pour the only real variables. 4 min Kalita Wave Where the V60 gives you a deep cone and free-flowing exit, the Kalita Wave does the opposite: a flat bed, three small holes, and a corrugated paper that holds itself off the walls. The brewer restricts flow on purpose. The grounds and the device share control. 4 min Chemex The Chemex is mostly known for its hourglass silhouette, but its real signature is the paper. Chemex bonded filters are 20–30% thicker than standard pour-over papers — they trap more oils, more fines, and slow flow noticeably. The brewer is a vessel; the filter does the work. 4 min Origami The Origami dripper is a folded ceramic cone with 20 vertical ridges, designed to fit either a V60 conical filter *or* a Kalita Wave flat-bottom paper. One brewer, two geometries — that's why competitive baristas keep landing on it. 4 min AeroPress The AeroPress is a steel cylinder, a plunger, and a paper filter — sold as a travel brewer in 2005 and quickly adopted by people who'd never travel with one. Its trick is that it sits across the filter/immersion line. Closed at the bottom by the filter and your stand, it's an immersion brewer. Once you press, water and grounds separate fast. The grind range it accepts is enormous, and the cup is clean but with body. 5 min Clever and Switch Both brewers solve the same problem: *what if you could steep like a French press, but drain through a paper filter*? The Clever Coffee Dripper has a gravity-triggered valve in the bottom — it stays closed until you place the brewer on a cup, and the cup pushes the valve open. The Hario Switch is a V60 with a manual valve. Same idea, different release mechanism. 4 min Cold brew Cold brew is filter coffee's slowest cousin. You drop coffee and cold (or room-temperature) water into a vessel, leave it for 12–24 hours, and then strain. No heat, no pour, no fuss. Time replaces temperature as the extraction lever. 4 min French press The French press is the cleanest expression of the immersion idea: ground coffee, hot water, a metal mesh, and time. The mesh holds everything bigger than ~150 microns; everything smaller — fines and oils — passes into the cup. That single design choice is what gives the French press its character. 4 min Moka pot Bialetti patented the moka pot in 1933 and the design hasn't changed much since. A bottom chamber holds water, a basket holds coffee, an upper chamber receives the brew. Heat the base on the stove; pressure builds in the bottom chamber as water heats; steam pressure pushes hot water up through the basket and into the upper chamber. It's a stovetop pressure brewer, not espresso — pressure tops out around 1.5 bar, where espresso machines run 9. 5 min Japanese iced (flash brew) The fastest way to a high-quality cold coffee is also the most counter-intuitive: brew a hot V60 directly onto ice. Flash brew (sometimes called Japanese iced or Tetsu Kasuya iced, after the WBrC 2016 champion who popularised it) replaces part of the brew water with ice in the carafe. The hot brew falls through the bed normally, then chills instantly on contact with ice — locking the volatile aromatics in the cup before they evaporate. 4 min

Pour patterns Where you place water on the bed decides how the bed extracts. Two things are at play, and they're separate: the **shape** you trace — center or spiral — and the **rhythm** you pour it in — one continuous stream or a series of pulses. You can pour a spiral continuously or in pulses; the shape and the rhythm are independent choices. 4 min Bloom strategies The bloom is when the foundations meet the recipe. Foundations gives you the *why*; here's the *how-much* and the *how*. 4 min Agitation Agitation is anything you do that moves water *through* the grounds rather than just placing water *on top of* them. It's the most under-discussed lever in pour-over and the easiest one to abuse. 5 min Drawdown The drawdown is the period after your last pour when water is leaving the bed but you're not adding any more. It's where most diagnoses happen — the bed reveals what your pour did, and the timing tells you whether the grind is right. 5 min Water minerality Coffee is 98–99% water. Whatever the water carries, the coffee shows. Most home brewers spend hundreds on grinders and pennies on water — that's backwards. 5 min Retasting Most brewers taste a coffee once, decide what it is, and never go back. That's how you build a static palate. Retasting — going back to the same coffee twice or three times across a week — is how you actually learn it. 4 min Scaling recipes A recipe that works for one cup doesn't always work for two. The math says it should — double the coffee, double the water, same ratio. The cup says it doesn't, and there are reasons. 3 min Channeling Channeling is when water finds a single path through the bed and uses it to skip past most of the coffee. The cup tastes hollow, sour, and under-extracted — but the bed *looks* like it brewed. It's the most diagnostic-resistant problem in pour-over because the timing often looks right. 5 min

Why cupping matters Cupping is the standardised tasting protocol the specialty coffee industry uses to evaluate coffees. It was codified by the Specialty Coffee Association in the 1990s and is the method behind every score on a bag of single-origin, every green-bean buying decision, and every competition. Unlike the brewing methods elsewhere in this app, cupping isn't designed to produce a pleasant cup. It's designed to produce a *comparable* one. 4 min The SCA protocol The Specialty Coffee Association cupping protocol is the lingua franca of coffee evaluation. It was published in the early 2000s and was the basis of every cupping score, every Q-grader exam, and every competition until November 2024 (when CVA 2024 replaced it — covered in the next article). The 2004 protocol still matters: it's the version most roasters trained on, and the one you'll see referenced everywhere. 4 min The CVA 2024 standard In November 2024 the SCA replaced its 2004 cupping protocol with the **Coffee Value Assessment (CVA)**, published as Standard 102-2024. It's the most consequential change to cupping in twenty years. Most of the mechanics stay the same; what changes is how you score and what the scores mean. 4 min Cupping at home You don't need a Q-grader certificate to cup. Three bowls and a kitchen scale will teach you more in an afternoon than a year of casual brewing. The point isn't to score; it's to *compare*. 4 min The triangle test The triangle test is a discrimination exercise: three identical bowls, two of one coffee and one of another, presented blind. The taster has to identify which one is different. It isn't about preference or scoring — it answers a single question: *can you actually tell these two coffees apart?* 3 min Hitting a TDS target Once you have a refractometer, cupping stops being purely sensory. You can measure the actual concentration of the brew (TDS, total dissolved solids) and use that to back-calculate the extraction yield. The Barista Hustle protocol is the most-cited standard for this — it targets **1.4% TDS** at 8 minutes after pour, with a fixed 11 g / 200 ml ratio. 5 min

Astringency A drying, puckering sensation on the tongue and inner cheeks — the same feeling unripe persimmon or strong black tea leaves behind. It's not bitterness and it's not acidity. It's a tactile flaw, not a taste, caused by polyphenols binding to the proteins in your saliva. 2 min Bypass Water that reaches your cup without passing through the coffee bed. In a pour-over, that's water poured against the wall of the dripper that runs straight down the filter, never touching the slurry — diluting the brewed coffee on its way through. 2 min Slurry The wet bed of coffee grounds and water sitting in the brewer during a pour-over. Not the dry coffee, not the brewed liquid below the filter — the muddy, swirling middle. 1 min Gooseneck kettle A kettle with a long, narrow, S-curved spout that lets you pour a thin, controlled stream of water exactly where you aim it. The shape borrows its name from the bird — the spout rises from the body, bends forward, and tapers like a goose's neck. 2 min WDT (Weiss Distribution Technique) A pre-brew step where you stir the dry coffee bed with a thin tool — a needle, a fine wire, an unbent paperclip — to break up clumps before water touches it. Named for John Weiss, the espresso enthusiast who popularized it as a way to fix uneven distribution in portafilters. 2 min Extraction The act of dissolving compounds out of ground coffee into water. Roasted coffee is about 30 % soluble — the maximum mass that water can theoretically pull out before what's left is just dry cellulose. Specialty filter brewing aims for **18–22 %** of that mass actually extracted, the window where the cup is balanced. 2 min Strength How concentrated the brewed coffee is — measured as **TDS** (total dissolved solids), the percentage of dissolved coffee mass per gram of liquid in your cup. A typical filter coffee lands between **1.20 % and 1.50 %** TDS. Espresso lives at 8–12 %. 1 min TDS (Total Dissolved Solids) The percentage of dissolved coffee mass per gram of liquid in your brewed cup. **1.30 %** TDS means 1.3 grams of coffee compounds are dissolved in every 100 grams of liquid. It's the number that quantifies what your tongue calls "strength." 1 min Immersion brewing A brewing approach where the ground coffee sits *fully submerged* in water for a defined time before the liquid is separated from the bed. The opposite of percolation, where water passes *through* the bed continuously. 2 min Percolation brewing A brewing approach where water passes *through* the coffee bed continuously and exits as brewed liquid almost immediately. Every pour-over method is percolation: V60, Chemex, Kalita, Origami, Orea, Tricolate. Espresso is also percolation, just under nine bars of pressure. 2 min Muddying A specific over-extraction symptom where the cup loses clarity and tastes thick, dull, and undifferentiated. Acidity collapses, the aromatics that should be sitting on top go quiet, and what's left is heavy roast and cardboard. The bean stops sounding like itself. 1 min Fines The smallest particles produced when you grind coffee — typically below 100 microns. Every grinder produces fines, even the best ones. The question isn't whether they exist; it's how many you get and how evenly they're distributed across the bed. 1 min Boulders The largest particles in a ground coffee bed — informal name for the chunks that didn't get fully broken down by the burrs. The opposite of fines. Visible to the naked eye in most home grinds: little gravelly bits sitting alongside the medium particles. 1 min Burrs The two cutting wheels inside a coffee grinder that fracture beans into a target particle size. They sit very close together, the gap calibrated to fractions of a millimeter, and the bean has to pass between them to come out the other side as ground coffee. 2 min Degassing The release of CO₂ trapped inside roasted coffee beans. Roasting produces gas as a by-product of the Maillard reaction; that gas slowly escapes through the bean's cell structure over the days and weeks after roast. Coffee is "degassing" the entire time it sits in the bag. 2 min Off-roast The number of days that have passed since a coffee was roasted. Specialty bags often print a roast date instead of an expiry date, and a coffee at "day 14 off-roast" was roasted exactly two weeks ago. 1 min Clarity A cup attribute that describes how distinctly the individual flavors come through. A clear cup lets you taste each note as a separate thing — citrus *and* florals *and* malt *and* finish — instead of one homogeneous brown blur. The opposite of muddied. 1 min Body The tactile weight of coffee in your mouth — what makes one cup feel like skim milk and another feel like cream. Body is independent from flavor and from strength; you can have a strong, light-bodied cup and a weak, heavy-bodied one. 1 min Acidity The bright, lively quality in a coffee that makes you salivate — analogous to the acidity in a green apple, a citrus fruit, or a glass of crisp white wine. In specialty coffee, acidity is a virtue, not a flaw. It's what separates a cup that tastes alive from one that tastes flat. 2 min First crack The audible *pop* a coffee bean makes during roasting when its internal moisture flashes to steam and forces its way out, fracturing the bean structure. Sounds like very faint popcorn — quieter, drier, more like cracking knuckles than corn popping. Happens around **196–205 °C** bean temperature, depending on the bean and the roaster. 1 min Second crack A second audible cracking event during roasting, around **224–230 °C** bean temperature, when the bean's cellulose structure breaks down further and oils start to migrate to the surface. The sound is louder, sharper, and more frequent than first crack — closer to the snap of breaking matchsticks. 1 min Roast defects Specific flavor faults that come from how a coffee was roasted, not from the green bean itself. Recognizable by their consistency: every bag from a roaster who's making the same mistake will share the same defect, no matter the origin. 2 min Green defects Faults present in the unroasted (green) coffee bean that no roast can rescue. Specialty grading systems exist precisely to count these — Q-grade and SCA both score a coffee partly by how few defects it contains per kilo. 2 min Siphon (vacuum pot) A two-chamber brewing device that uses heat-driven vapor pressure to push water up into the coffee bed, then vacuum to pull the brewed liquid back down through a filter. Also spelled *syphon*. Looks dramatic — water levitates between glass chambers — and works on a simple physics principle. 2 min Refractometer A small handheld device that measures the refractive index of brewed coffee — how much the liquid bends light — and converts that into a **TDS** percentage. Plug TDS, brew water, and dose into an extraction calculator and you get the **extraction yield**: the percentage of bean mass that actually dissolved into your cup. 1 min Bypass ratio The percentage of total brew water that didn't pass through the coffee bed — water that fell down the side of the filter, or water added directly to the served cup, never touching the slurry. A 0 % bypass brew has every drop interact with the grounds. A 30 % bypass brew has 30 % of its water arrive at the cup as plain hot water that just dilutes the rest. 1 min Specialty coffee A category — not just a marketing label — defined by a measurable cup score. The Specialty Coffee Association sets the threshold: a coffee that scores **80 or above on the 100-point cupping scale** can call itself specialty. Below 80, it's commercial. 2 min Third-wave coffee The cultural and commercial movement that re-positioned coffee from a commodity drink into a craft product, beginning roughly in the late 1990s and crystallizing through the 2000s. The name borrows from beer and food culture, where each "wave" describes a similar shift toward provenance and quality. 2 min Pulse pour A pour-over technique where you split the total water into multiple discrete pours separated by short pauses. The bed is allowed to drain partially between each pulse — water level drops to roughly the top of the slurry — and then you pour again. Common shapes: 4 pulses, 5 pulses, sometimes 6. 1 min Continuous pour A pour-over technique where, after the bloom, you maintain a single steady stream of water onto the bed without stopping until the target weight is reached. The opposite of a pulse pour. The water level above the slurry is allowed to rise and stabilize, then drain through together at the end. 1 min Swirl A specific agitation technique where you grip the brewer (or its server) and rotate it in a quick circular motion to redistribute the slurry without breaking up the bed structure. Most commonly used right after the bloom or after each pour in a pulse-pour recipe. 1 min Pre-infusion A short initial water contact phase before the main extraction begins. The grounds are wetted with a small amount of water, then allowed to sit briefly so they can absorb water, swell, and release CO₂ before the bulk of the brew water arrives. 1 min Puck The disc of spent grounds left in the brewer at the end of a brew. The word comes from espresso — where the compacted, wet hockey-puck-shaped cake of grounds is the literal physical object you knock out of the portafilter — but it's now used for filter coffee too. 1 min Tasting note A short descriptor on a coffee bag — "**blueberry, dark chocolate, brown sugar**" — meant to tell you what flavors you should expect to find in the cup. Roasters write them based on cuppings of that specific lot. They're a *prediction*, not a guarantee, and they read better as a vocabulary scaffold than as a literal taste menu. 1 min Varietals The botanical varieties of *Coffea arabica* — like grape varieties for wine, or apple varieties for cider. Two coffees from the same farm, processed the same way, will taste different if they're different varietals. Specialty bags often print the variety alongside origin and processing. 2 min Elevation The altitude (in metres above sea level, MASL) at which a coffee was grown. Specialty bags routinely print this — "1,800 MASL," "1,950 MASL" — because elevation is one of the strongest predictors of cup quality in arabica. 2 min Water activity A measurement of the *available* water inside a coffee bean — water free enough to participate in chemical reactions, microbial growth, and aroma loss. Written **Aw**, on a scale from 0 to 1 where 1 is pure liquid water and 0 is bone dry. 2 min Single origin Coffee that comes from one identifiable place. The exact precision of "one place" varies by usage: 1 min Blend Coffee made by combining beans from two or more origins, varieties, or roast curves into a single bag. The opposite of single origin. Done well, blending creates a cup that's larger than its parts — sweetness from one component, body from another, brightness from a third. Done poorly, it's a way to hide low-quality coffee inside a more interesting one. 1 min Microlot A small, separately-processed batch of coffee from a single farm — typically a few hundred kilos at most — kept apart from the farm's larger production because it's expected to score higher in cup quality. Microlots are the way specialty roasters access the most distinctive coffees a producing region has to offer. 1 min Dose The amount of dry coffee — measured by weight in grams — that you put into the brewer for a single brew. The starting point of every recipe. "Use a 15 g dose" means you'll grind 15 grams of beans before water touches anything. 1 min Direct trade A sourcing model in which a roaster buys green coffee directly from the producer — farm, cooperative, or producer group — without commodity-market intermediaries setting price or terms. The roaster typically visits the farm, knows the producer's name, and negotiates a price tied to cup quality rather than to the C-market. 2 min Fair Trade A certification standard that guarantees a minimum price floor for green coffee, regardless of where the C-market futures price sits. Created in the late 1980s, formalized by Fairtrade International in 1997, and now visible on most supermarket coffee shelves through the round Fairtrade Mark. 2 min Decaf (decaffeinated coffee) Coffee beans that have had ~97-99% of their caffeine removed before roasting. The bean still tastes like coffee — most of the flavour compounds aren't caffeine — but it won't keep you up at night. Specialty decaf has gotten dramatically better in the last decade as the decaffeination processes have improved. 2 min Crema The reddish-brown layer of foam that sits on top of a freshly pulled espresso shot. Made of CO₂ trapped inside a colloidal suspension of microscopic coffee oils, melanoidins, and dissolved compounds. Crema only happens under pressure — pour-over and immersion brews don't produce it because they don't extract under nine bars. 1 min Portafilter The metal-handled basket-holder that locks into an espresso machine's group head. The barista grinds coffee into the basket, tamps it, locks the portafilter into the machine, and water is forced through under pressure to make espresso. Without a portafilter, an espresso machine is just a kettle. 1 min Tamping The act of pressing ground coffee in an espresso portafilter into a flat, level, evenly compacted puck before locking the portafilter into the machine. Without tamping, the bed has air gaps and uneven density; pressurized water finds the path of least resistance, channels through, and extracts unevenly. 1 min Hand grinder (manual grinder) A coffee grinder powered by a hand crank rather than an electric motor. Pour a dose into the hopper, twist a knob to set grind size, attach the crank, and spin until the chamber is empty. Specialty hand grinders use the same conical or flat burrs as electric models — they're not a compromise on grind quality, only on speed and effort. 2 min