PREPARATION & TROUBLESHOOTING

Preparation and troubleshooting: frequently asked questions

There are no espresso laws. No espresso police. The only goal is a coffee that tastes good to you. Making espresso is like cooking at home: you experiment, use the spices and cookware you like, and cook the way you find good. We at the Coffee Coaching Club think about coffee from two perspectives: the extraction chemistry and the biology of perception. That's our point of view, one of many. There's no ultimate opinion in the coffee world. Everyone has to find out for themselves what works. The only thing that matters: does the coffee taste good or not?

Before you dive deeper: in our Sensory World you can experiment yourself with interactive simulators to see how extraction and grind size affect the flavor profile. Playful, sensory, easy to follow.

How does the Coffee Coaching Club think about espresso preparation?

We don't measure time. We don't follow rigid recipes. We extract according to the ratio of ground coffee to extract. The standard ratio is 1:2, so for example 18 g of ground coffee to 36 g of espresso in the cup. But other ratios are possible too and can taste great, depending on the bean, the roast, and your personal taste.

In our cafés in Bern and Zurich, we sometimes extract for up to 120 seconds. We grind very fine and extract slowly and steadily. That works because we use reliable coffee grinders that deliver an even grind, and espresso machines with a stable pump and precise temperature control. At the same time, Turbo shots with just 5 to 10 seconds of extraction time can taste fantastic, for example with 100 percent robusta beans. That's our way, but it's not the only one. Other roasteries and baristas work with completely different methods and get great results. There's no right or wrong. There's only: does it taste good to you?

Why doesn't my espresso taste the way I want it to?

There are two ways to look at this question. The first is the extraction chemistry: what happens physically and chemically when hot water flows through ground coffee? The second is the biology: how does your body perceive aromas, and why do you perceive them the way you do?

On the chemical side: coffee contains over 800 aroma compounds, which release at different points during extraction. First the fruity acidity, then the sweetness and body, and finally the bitter compounds. If your espresso doesn't taste good to you, it almost always has to do with the ratio in which these groups end up in your cup. The variable you can control most easily: the ratio of ground coffee to extract and the grind size. Our Extraction Simulator shows you in real time how every change affects the flavor profile.

On the biological side: every person perceives aromas differently. Your genetics and your taste conditioning determine whether you find a coffee pleasant or unpleasant. That's not a flaw, that's nature. There's no objectively perfect espresso, only your perfect espresso. What we describe here is our perspective. Others see it differently, and that's just as valid.

What does biology have to do with enjoying coffee?

More than most people think. The perception of aromas is a biological process governed by survival. Your brain constantly evaluates: is what I'm eating or drinking right now safe?

One example: temperature. The hotter the espresso, the more your brain focuses on protecting the receptors on your tongue. Aroma perception moves into the background because the brain prioritizes information about temperature. That's why you taste less aroma but more body in hot coffee. Let the same espresso cool a little, and the aroma spectrum opens up, because your brain lowers its protective response and passes the aroma signals on to your conscious awareness.

The same principle applies to bitterness and sweetness. Your body has learned: extreme bitterness can mean poison. When bitterness is too dominant, your brain suppresses the perception of sweetness at a neural level — even though the sweet compounds are still chemically present. Lower the bitterness, and the sweetness “appears” on its own. That's not a matter of taste, that's neuroscience. In our Sensory 1×1 we explain these mechanisms in detail.

Beyond that, smell, audio-visual perception, and touch also play a role. The choice of vessel, its material, its color, its temperature influences how you perceive the coffee. An espresso from a thick-walled, preheated ceramic cup tastes different than the same espresso from a thin glass. Not because the coffee changed chemically, but because your brain evaluates the overall situation differently. Sensory research calls this cross-modal perception — your brain combines all sensory impressions into a single taste picture.

Can I replicate an espresso shot exactly?

No, and that's a good thing. You'll never pull the same shot twice, because you'll never grind the same bean again. Every single bean is different: a different size, grown at a different spot on the plant, and therefore ripened slightly differently. There are minimal variations in roasting too. Not every bean in a batch gets roasted exactly the same way — that's physically impossible.

Add to that external factors that directly affect extraction. The humidity changes how the ground coffee behaves: on humid days it swells more, the puck becomes denser, and extraction slows down. On dry days, the opposite is true. Temperature and air pressure play a role too. Anyone who pays close attention notices differences between morning and afternoon, between summer and winter, between a rainy day and a sunny one.

And then there's the human factor. Your perception is constantly changing. You're never again the person you were yesterday. Your taste preferences keep developing, your body changes, your mood influences how you perceive aromas. The weather, how well you slept, what you ate before, whether you're stressed or relaxed — all of this changes how the espresso tastes to you. The same shot, on the same day, with the same bean, can taste different at 8 in the morning than at 15h in the afternoon.

Espresso extraction is complex, but it's not rocket science. There's no right and no wrong, only coffee that tastes good or doesn't. Everything you read here is our opinion, one of many in the coffee world. Find your own way. Let's simply enjoy it.

What influences the taste of my espresso the most?

From the perspective of extraction chemistry there are a few variables that have a particularly big impact:

The ratio of ground coffee to extract. Our standard is 1:2 (e.g. 18 g in, 36 g out). Shorter ratios like 1:1.5 give a more concentrated, body-forward shot. Longer ratios like 1:2.5 or 1:3 emphasize clarity and fruity notes. Experiment here first. In our Extraction Simulator you can see directly the effects of different ratios.

The grind size. We tend to grind very fine and extract slowly and steadily. A finer grind size increases the contact surface between water and coffee and enables a more even extraction. The prerequisite for this is a grinder that delivers an even grind, from brands like Comandante, Varia, Mahlkönig or Weber Workshops.

Brew temperature. The higher the temperature, the more body you perceive. The lower the temperature, the more aroma and less body. At the same time, body can make the aroma feel more harmonious. There's no correct value, only the value that works for this bean and your taste.

The grinder's speed. Higher RPM produces more body in the espresso, lower RPM emphasizes aroma. Grinders with variable speed or deliberately low RPM from Option-O or Weber Workshops give you an extra lever here. Our Grinder Simulator shows you how speed, burr type, and disc size affect the flavor profile.

The choice of basket. A different basket changes the espresso as fundamentally as using a different bean. Hole size, hole distribution, and basket geometry affect the flow rate and therefore which aroma groups get extracted preferentially. Experiment with different baskets from IMS or VST.

The Puck Screen. A fine metal screen on the coffee puck distributes the brew water more evenly and reduces channeling. The result: less bitterness, more perceived sweetness. Thicker Puck Screens absorb more heat and noticeably lower the effective brew temperature, thinner ones only slightly. In the Extraction Simulator you can compare the difference with and without a Puck Screen directly.

These are the variables we consider particularly relevant. Other baristas weight things differently, and that can lead to the goal just as well. In the end, only one thing matters: does the coffee in your cup taste good?

Why does my espresso feel thin even though it has body?

This is one of the questions that has occupied us the most in recent months. The answer lies not in extraction chemistry, but in the biology of perception.

Your brain evaluates fullness not only through mouthfeel (the physical viscosity), but combines it with retronasal aromas into a single impression. Sensory research calls this cross-modal perception. An espresso with high body but without sweetness and without aromatic depth is perceived as thin and watery — even though it's not physically thin. Conversely, an aromatically rich coffee feels fuller, even at the same viscosity.

This means: body alone isn't enough. Body without sweetness and aroma doesn't feel “full.” That's why it's so important not only to optimize viscosity (grind finer, higher dose), but also to create the conditions for sweetness and aroma — even extraction, the right temperature range, a Puck Screen against channeling. In our Sensory 1×1 we explain the six flavor dimensions and their interactions in detail.

Why is puck prep so important?

Puck prep is the preparation of the coffee puck in the portafilter before extraction. It's so crucial because it determines whether the water flows evenly through the ground coffee or seeks out channels. Uneven flow means part of the coffee gets over-extracted and another part under-extracted. You taste both at the same time, and that doesn't give you a clean, well-defined cup.

Our puck prep sequence: first distribute the ground coffee with a WDT tool (fine needles moved in circular motions through the grounds) and break up clumps. Then, with a leveler create an even surface. Finally, with a calibrated tamper compact it. We prefer to work with tools from Normcore and Weber Workshops, because they deliver reproducible results.

When you grind very fine and extract slowly, as we do in our roastery, clean puck prep becomes even more important. The finer the grind, the greater the risk of clumping and therefore of channeling. You'll find good equipment for puck prep in our barista equipment range. Which accessory makes sense for which step, we show you in detail in our guide Puck prep accessories.

Why do I need a good coffee grinder?

The coffee grinder is the most important piece of equipment in your setup, even ahead of the espresso machine. That's at least our conviction, and many in the coffee world share it. Others put the machine first, and that can work too. The reason for our stance: an even grind is the prerequisite for a controlled extraction. When particle sizes vary too widely, large particles get under-extracted and small ones over-extracted, at the same time, in the same shot. That results in an undefined taste that's neither clear nor harmonious.

In our roastery, we deliberately grind very fine and extract slowly. That only works because our grinders deliver an extremely even grind. With a grinder that has a wide particle distribution, the same fine grind size would clog the puck.

Another factor: the grinder's RPM. Higher speed tends to produce more body, lower speed emphasizes aroma. Grinders with slow-turning burrs from Comandante (hand grinder), Option-O or Weber Workshops offer a sensory advantage here. Electric all-rounders from Eureka, Mazzer, Fiorenzato or Mahlkönig deliver reliable results day to day. For hand grinders, we also recommend Varia and Timemore.

Is there a best burr set?

No. Burrs are like engines in cars: each has its own character, and which one you like best is subjective. A flat burr set (Flat Burr) tends to produce a different flavor profile than a conical one (Conical Burr). Within these categories, results vary widely again depending on geometry, material, coating, and burr size.

Flat burrs often emphasize clarity and separation of aromas. Conical burrs tend toward more body and a rounder cup. But these are tendencies, not laws. A large flat-burr grinder from Mahlkönig tastes fundamentally different from a smaller flat-burr grinder from the same brand. And a Comandante with a conical burr set produces a completely different espresso than the conical burrs in a Varia hand grinder.

Add to that aftermarket burr sets like those from SSP, which can completely change a grinder's character. It's like engine tuning: same grinder, different burrs, different coffee in the cup. There's no universally best burr set, because it's subjective whether you like the flavor profile or not. Our Grinder Simulator shows you how burr type, edge geometry, RPM, and alignment affect the flavor profile — explore the combinations and compare. And if you'd like to test different grinders side by side and taste the difference directly in the cup, there's our Espresso Machine and Grinder Comparison for that.

How important are the design and feel of coffee equipment?

More important than most people think, and there's a real reason for that. Coffee doesn't start with the first sip. Coffee starts the moment you look at your equipment, touch it, and start the process. Picking up the grinder, locking in the portafilter, pulling the lever. These are the moments that make coffee fun.

Whether you find your equipment beautiful, whether it feels good, whether the build quality speaks to you — that influences your emotional state, even before the first drop of espresso falls into the cup. And your emotional state influences how you perceive the coffee. That's not esoteric, that's biology: your brain doesn't evaluate enjoyment in isolation, but in the context of the entire experience.

That's why, at the Coffee Coaching Club, we place great value on carrying equipment that's not only functionally convincing but also aesthetically and tactilely enjoyable. A grinder from Weber Workshops looks like a design object and feels like a precision instrument. A Flair Espresso has a ritual that makes the whole process deliberate and unhurried. A machine from Arkel is a statement in the kitchen even before you turn it on. These aren't minor details. They're part of the enjoyment of coffee.

Why do I need a good espresso machine?

The espresso machine has to reliably deliver two things: stable temperature and even pump pressure. Both directly influence which aroma compounds are released from the coffee and in what balance they end up in your cup.

Temperature stability is crucial, because even small fluctuations change the character of the espresso. Higher temperature emphasizes body, lower temperature emphasizes aroma. If the machine fluctuates during extraction, you get an unpredictable mix. Dual boilers from La Marzocco or Arkel offer the highest precision here.

Pump stability matters because we extract slowly and evenly. If the pressure fluctuates, the flow rate through the puck changes, and extraction becomes uneven. Machines with a rotary pump or high-quality vibration pumps with pressure control deliver the best results here. Mind you: these are the properties we prioritize for our style of preparation. If you work differently, you may need different equipment. The coffee in the cup decides, not the spec sheet.

More on this in our deep dive on heating systems.

Which water should I use for espresso?

Water makes up over 90 percent of your espresso and has an enormous influence on taste and the machine's lifespan. The mineral composition of the water determines which flavor substances get released from the coffee and how they taste in the cup.

Water that's too hard (lots of limescale) scales up your machine and makes the espresso flat and dull. Water that's too soft or distilled produces an empty-tasting espresso, because the minerals needed for extracting certain aroma groups are missing. The ideal range is a total hardness of 50 to 100 mg/l. In Bern and Zurich, tap water is noticeably harder.

Your options: a water filter like the systems from BWT or Brita, water you mix yourself from distilled water and a mineral solution for full control, or mineralized bottled water with a suitable composition. We have a detailed guide on this: Composing your own coffee water.

How do I properly clean my portafilter machine?

Regular cleaning is essential for good taste and a long lifespan.

After every shot: rinse the portafilter and basket briefly under running water. Flush the group head with a short blank shot. Wipe the steam wand immediately after use with a damp cloth and briefly purge steam so no milk residue dries on.

Daily: backflush without detergent — flush through several times briefly to release fresh coffee oils from the group head. Roughly every 50 shots (at home): backflush with detergent. Insert the blind basket, add cleaning powder like Puly Caff, start and stop the brew cycle several times, then rinse afterward without detergent. In commercial operation (café/restaurant): due to the much higher number of shots, do it daily with detergent. You'll find more background on the frequency — and why it differs between home and commercial use — in our detailed guide Backflushing correctly – how often, really.

Don't forget the coffee grinder: regularly clear the burrs and grinding chamber of old coffee grounds with a brush or a blower. Old coffee grounds oxidize and pass rancid aromas on to fresh ground coffee. Our cleaning range has everything you need.

How do I properly prepare filter coffee?

Filter coffee is the purest way to experience the aromas of a bean. Without pressure and with a longer contact time, filter coffee brings out especially fine, fruity notes that sometimes disappear behind the body in espresso.

Here too, our basic philosophy applies: there's no right or wrong. Discover what tastes good to you. As a starting point: use a medium to coarse grind size (noticeably coarser than espresso). A good starting ratio is 60 to 65 grams of coffee per liter of water. The water temperature ideally sits between 92 and 96 degrees.

For pour-over methods like Hario V60 or Chemex: start with a bloom (wet the ground coffee with double the amount of water and let it swell for 30 seconds), then pour in slow, circular motions. For French press or AeroPress different techniques and grind sizes apply. How AeroPress and Hario V60 differ in a direct comparison and which method fits better into your daily routine, we show you in detail in AeroPress vs. Hario V60 – filter coffee compared. In our showrooms in Bern and Zurich you can experience different filter methods and compare the differences directly in the cup.

Discover for yourself: our interactive simulators

Sometimes a slider says more than a thousand words. We've built two interactive tools in our Sensory World based on the insights from our roastery. No video, no article — you move the parameters and see instantly what happens to body, sweetness, aroma, and bitterness.

The Extraction Simulator — temperature, dose, ratio, grind size, and Puck Screen: how they change your flavor profile in real time. With context-dependent product recommendations.

The Grinder Simulator — conical or flat? Classic or modern? How speed, disc size, and alignment determine particle distribution and therefore taste.

You'll find the science behind the simulators in our Sensory 1×1 — our glossary on body, sweetness, aroma, cross-modal perception, and neural suppression.

New: technical articles with animations

Eight in-depth articles on brew groups, water chemistry, grinding, Pre-Infusion, Flow-Profiling, Puck-Prep and dosing — each with the original studies and short animations.

Saturated Group vs. E61 — what thermal stability really does.

Water chemistry for Dualboiler — magnesium, calcium and alkalinity.

Bimodal vs. unimodal particle distribution — Fines, permeability and mouthfeel.

RPM-Profiling on the coffee grinder — what burr speed really changes.

The chemistry of Pre-Infusion — the first ten seconds in the puck.

Flow-Profiling for light roasts — controlling fruitiness without losing body.

WDT and Self-Leveling-Tamper — the physics behind even resistance.

Gravimetric brewing — why volumetrics reaches its limits with fresh coffee.

More questions? Discover our other FAQ sections: buying advice | brands and products | service and shipping. Or start directly in our Sensory World.