October 8th, 2019 / 6 min read

The Sloppy Puck Myth

You’ve done it. You saved up enough money to purchase a new super-automatic espresso machine. The day comes, you open the box, and in your excitement, you plug it in to begin brewing up a storm.

You turn on the machine, pushing the power button to wake the machine from its sleep. The first ‘ESPRESSO’ button is pressed and the back-light illuminates your cup, creating an almost halo-glow and indicating your inaugural brew has begun. The sound of the burr grinder is music to your ears as the aroma of espresso slowly fills the room. Your first sip commences, and you break out in a smile from cheek to cheek.

A few days pass and your happily caffeinated during the moments that matter most. Suddenly a notification appears on your machine and it’s time to empty the coffee waste bin. “I wonder what the pucks look like…” you ponder. With your hand you slowly open the door to view these magnificent pressure-created creatures and what do you discover? Soupy, wet, fragmented pucks.

Madness ensues… or does it?

Chances are, if you’re an owner of a super-automatic espresso machine, sloppy coffee pucks are something you’ve experienced. But why do they occur? And are they truly an indicator of a poorly run espresso shot? We’re here to help address this dubious question.

A number of variables

It’s important to note that there are many variables that impact puck consistency from the terroir of the bean, the roast, the age/storage conditions, exposure to air and sunlight, to the brewing parameters. These levers impact taste, crema, acidity, puck consistency and more. For example, if your apartment is hot and humid, coffee grounds may absorb water from the air and the water from the espresso machine will not penetrate as quickly leading to a sub-optimal extraction and may lead to a watery puck.

How to read your pucks

The puck is the fun round disc of coffee that is left after your espresso has been pulled. If everything goes right often it will be a solid dry-ish disc of coffee. If it’s wet and soggy in the waste bin, not to fear, you might just want to check a few things. First, it’s important to understand the dispensing method on super-automatic espresso machines.

Fresh ground coffee is compressed into the brew group for brewing to take place then water is forced post-tamping through the ground beans with pressure. After brewing is complete the puck of used coffee gets deposited into the waste bin via a mechanical kick. If previous pucks are in the bin this can cause these newly formed pucks to break into pieces versus staying intact. After this automated cycle, some water ends up in the coffee ground container which can also impact pucks resting inside.

A straightforward way to think about your pucks is via the settings on your machine. The user chooses the liquid volume that is dispensed using the machine’s menu settings. As you change your machine settings this will influence the taste of your coffee and consistency of the coffee puck. For example, try changing your grinder settings (finer), coffee dosage (higher), and/or the coffee volume (less) and try again. Trying different settings is important to fit your preferred taste profile and will ultimately impact the coffee puck’s shape and firmness.

A couple of things to look out for in your settings: 1) a coarse grind leads to less strong coffee and a waterier puck 2) a higher coffee volume leads to less strong coffee and a waterier puck. On our TK-01 we recommend that the coffee dosage is either 11 or 12 grams to increase the weight while brewing. Nonetheless, water is a critical part of the brewing process — espresso cannot exist without it!

Lastly, it’s important to remember that the dispensing methodology of a super-automatic brew unit greatly impacts what a coffee puck looks like after brewing. Because of the mechanical kick and dredge bin structure, the puck does not necessarily need to be intact to have been brewed properly. Being aware of all these little differences will allow you to more adequately determine if and when your TK-01 needs any troubleshooting.

It’s what’s inside that counts

What is inside the cup is what matters most. With the variability of coffee beans, roast level, rinse cycles, etc., the puck dryness can vary quite a bit. The more important thing to monitor is that the extraction isn’t blonde from the beginning, a wet puck is far less wicked than an uneven extraction. Your espresso shot should start with a rich brown color and result with a crema that is about one-tenth of the espresso.

Monitoring the grind size can help here as well. If the grind is too coarse it will be too loose and water will flow through too quickly which can lead to a weak under-extracted shot with little crema. If the grind is too fine it will be too dense and water will struggle to flow through at all, leading to an over-extracted and bitter espresso shot.

Playing around with the grind settings is a necessary step to ensure your super-automatic espresso machine yields an optimal brew. For espresso, you would want a finer grind, on the TK-01 we recommend the grind size to be around 1 or 2 on the dial. A coarse grind would suit you better for things like a French Press and cold extraction. If you are getting good shots out of your machine then the wet puck isn’t necessarily a cause for alarm.

Don’t forget to clean

Make sure to clean your machine sooner rather than later. Frequently dumping your coffee waste bin can help limit the number of wet sloppy pucks. These machines get quite hot, and residual heat inside creates moisture that traps in the waste bin. Moisture left internally causes newly formed pucks to become wetter and break.

Periodically, it is important to rinse your brew unit to get rid of any residual mess in the basket. Once a week running hot water through the top of the brew unit and gently patting it dry with a towel should help keep your machine brewing nice and neat. As you would with a car, routine maintenance of your super-automatic espresso machine is vitally important!

To sum up

In the end, the most important things to monitor are (1) that the coffee being extracted isn’t blonde from the beginning (i.e. it should start with a rich brown color) (2) the resulting crema and (3) the taste.

Compact pucks are a good sign of a full-balanced extraction, but even the same beans in the hopper can vary in extraction from shot to shot. This happens even in the $10K+ commercial-grade machines with things like channeling, grind variability, etc.

Observe the extraction into your cup and not just the coffee pucks. Not saying that pucks aren’t important, just more of an indicator than a golden rule when brewing espresso on a super-automatic machine. If you are enjoying the taste, that is by far the most important. 😉

Myth debunked. Partially.


Terra Kaffe Team


At Terra Kaffe we are committed to furthering the growth of conscious consumption by reducing waste from coffee pods and brewing from fresh whole beans. Learn more about our bean-to-cup espresso machine here.


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