A wet coffee puck can ruin a good cup of coffee. If you notice the puck is wet, it’s an indication that the espresso isn’t up to par and have you screaming: “Why is my coffee puck wet!“.
Since a wet espresso puck means that the grounds didn’t fully extract, the espresso will turn out weak instead of rich and intense.
When the pressure in an espresso machine meets the proper puck resistance, the grounds extract as intended.
A wet coffee puck can put a damper on your day. The good news is that there are several ways to avoid a wet coffee puck.
Common reasons for a wet espresso puck include; too little espresso in the portafilter, wrong grind size, uneven distribution of grounds, and air pockets due to improper tamping.
Note: I use the terms Coffee puck and Espresso puck interchangeably throughout this article.
The Grind is Too Coarse
A good way to identify if a coarse grind is an issue is if you notice that the espresso brews at lightning speed but results in a thin, watery cup of coffee while your puck is a soggy mess.
If you use pre-ground coffee, check that it’s the right grind for espresso machines. Much pre-ground coffee is marketed for espresso machines but is too coarse for an upscale espresso machine.
Espresso is sensitive to what kind of grind quality is used. When coffee particles are too coarse or are uneven in size, this results in a soggy puck. Finely and evenly ground espresso is crucial to getting a good brew result.
Grinding your own espresso is the best way to ensure that you get the grind right. To do this, you’ll need a good espresso grinder that has a fine grind capacity, offers fine settings, and creates a tight grind distribution.
While this type of precision technology is more expensive than basic grinders, you’ll find that a proper espresso grinder makes a big difference for the puck and brew quality.
Wrong Size Portafilter / Espresso Filter Basket
If your grind is on target, one of the main reasons behind a wet puck is a portafilter (espresso filter basket) that isn’t filled enough. Using the wrong size compared to the level of coffee grounds won’t offer the right resistance for an espresso machine’s pressurized hot water system. This results in a soggy puck.
Many baristas like to use an espresso recipe that calls for a certain size grind. If you don’t want to change your espresso recipe, the best thing to do is to get the right size basket that fits the ground amount that you use.
You can pick up espresso baskets from IMS or VST since both these brands make quality espresso baskets. Most filter baskets measure 58mm in diameter, while a few others take different sizes. Checking to make sure that you get the proper size for the machine will make all the difference in the world.
Getting a basket size that’s the right fit for your recipe will not only create a dryer puck, but it will also result in espresso that tastes stronger and better.
Not Tamping Correctly
Another issue that causes a wet puck is loosely-packed grounds. Espresso grounds need to be compacted into the machine’s filter basket. When you tamp the grounds down, it presses the coffee particles together. Proper tamping ensures that the coffee particles stay in a tight clump when the hot water hits the puck.
Improper tamping results in a loose puck that causes a weak, watery brew. You can fix this by making sure that the grounds are firmly tamped into the coffee puck.
Just tamping firmly is not enough. You’ll also want to make sure that your basket size is proportionate to the coffee grounds used and that the grind is the right size for an espresso brew.
A coffee tamper will help you get the job done by compressing the loose coffee dose into a tight cake.
Check that your tamper is the proper diameter to fit closely into the filter basket. A tamper that’s too big won’t fit in your basket while using one that’s too small means that you won’t get the puck fully tamped down.
Most baristas favor 30-50 pounds for tamping force. When you press down and don’t feel the grounds give anymore, then you’ve used the correct pressure amount. A loose puck before brewing means a wet, soggy puck afterward. If you’ve done it right, your coffee grounds should look like a flat, tight cake prior to brewing.
Unequally Distributed Grounds
Skip a soupy puck that’s a mess to clean and doesn’t make a strong espresso brew. You can avoid this scenario by making sure that the grounds are distributed evenly, without any clumps, in the filter basket after tamping. A dosing funnel can help you make an even coffee bed instead of dumping the ground coffee into the basket by hand.
Check that the grounds have the same density from top to bottom and side to side in the basket. If areas on the puck have a lower density, they will offer less resistance to the high-pressurized water used by the espresso machine to create a proper brew. When the puck has less resistance, the water penetrates and flows through the coffee bed too fast.
Low resistance and fast water filtration increase erosion in areas that have empty pockets. This creates uneven extraction and weak, bitter espresso because some areas are over-extracted while other parts of the puck aren’t extracted at all.
If you think that uneven distribution is causing a wet puck to occur, use an espresso stirring tool to break up clumps of coffee and spread the grounds evenly.
Start at the bottom and stir in small circles until you’ve stirred the entire basket to break up any lingering lumps. Slowly pull out the needles as you go so that the top of the coffee grounds also turns into an even surface.
There Are Air pockets
By now, you’ve probably noticed a pattern in the mistakes that can cause a wet coffee puck.
Grind that doesn’t fit closely together, uneven distribution, clumps, and too much space are all culprits that can ruin the espresso process. A final mistake to avoid is allowing air pockets in the puck before it goes into the machine. When water hits an air pocket, this makes the grounds float around in the basket.
If you’re having trouble getting all the air pockets out, consider using a puck screen.
A puck screen is an extra filter that fits on top of the coffee puck. This helps press the puck together, so it doesn’t come loose. Since a puck screen also takes up more room in the basket, it helps prevent extra water from swimming around in the puck. It also helps water distribute more evenly to create better extraction.
Final Thoughts On Wet Coffee / Espresso Pucks
A wet puck isn’t necessarily an issue if you’re happy with the results. In most cases, a wet puck not only creates a mess to clean up but also means that the espresso didn’t turn out optimally.
When espresso finishes brewing, the puck should look like a hard, dry cake that is easily dumped out. If yours doesn’t look like that, then tweaking a few things from grind size to distribution and tamping can make a big difference.
With a little work, you can identify which of these often-overlooked mistakes is causing the issue and change the situation to create a delicious and balanced cup of espresso.
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