Why Does the Coffee Puck Stick to the Portafilter or Group Head?

Ever pulled an espresso shot only to find the coffee puck stuck to your machine's group head?

It happens to the best of us—one moment you're dreaming about your perfectly extracted espresso, and the next, you're scraping a stubborn puck off the shower screen. I’ve noticed this issue cropping up more frequently in conversations with home baristas, and honestly, it can be frustrating. Let’s talk about why this happens and how you can fix it.

Why does your coffee puck stick?

There are a few main culprits here, and from what I’ve seen, they're pretty common among home baristas.

Overdosing the coffee basket

One of the biggest reasons your coffee puck sticks to the group head is overdosing. When you pack in too much coffee, the puck expands, pressing against the shower screen. The puck gets suctioned to the group head after the extraction, making it difficult to remove. If you’re consistently seeing your coffee puck stuck, try slightly reducing the amount of coffee you’re dosing into the basket. Typically, for home espresso machines like the Breville Barista Express, doses around 16-17g work well, as I’ve seen in conversations like this detailed thread.

You might also benefit from switching to a precision basket that can give you more consistent extractions.

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Grinding your coffee too fine

Another reason your coffee puck might be sticking is the grind size. If your grind is too fine, it creates extra resistance during extraction, effectively vacuum-sealing the puck to the group head. I’ve noticed that coarsening your grind just slightly can make a significant difference. Aim for a grind that allows your shot to pull within the standard 25-30 seconds range. Here's a handy video I found that discusses adjusting grind size to prevent puck sticking.

Tamping pressure inconsistencies

How you tamp your coffee also matters—a lot. Uneven or excessive tamping pressure pushes the coffee against the screen, creating conditions ripe for sticking. Personally, I’ve found huge improvements by using a self-leveling tamper. It ensures consistent pressure and a level puck, making it far less likely to stick to the group head.

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Distribution issues

Proper distribution of coffee grounds can be a game changer. Poor distribution leads to uneven extraction, resulting in that frustrating stuck puck. The solution? Using a wdt tool to evenly distribute the coffee grounds before tamping helps massively. I’ve seen firsthand how this simple step prevents puck sticking almost entirely.

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Use of puck screens

Puck screens are another fantastic solution. By placing a puck screen on top of your coffee before extraction, you prevent direct contact with the group head, completely removing the sticking issue. If you're regularly facing stubborn pucks, it's probably worth giving puck screens a try. Users across forums like this one swear by them for exactly this reason.

Keeping things clean

Beyond these factors, keeping your espresso machine clean is crucial. Old coffee oils and residue build up on your shower screen over time, making the puck stickier. Regularly cleaning your machine’s shower screen, group head, and portafilter basket will prevent unnecessary sticking and extend your machine's lifespan. Here's a great resource I found on keeping your espresso machine clean.

Does your machine matter?

Yes, your machine can influence this. Different machines have varying basket sizes and group head clearances. For example, Breville machines (like the Barista Express or Bambino) are known to be a bit more sensitive to overdosing because of their basket design. Using specific accessories tailored to your machine's size and brand, such as a bottomless portafilter, can also give you insights into what might be going wrong during extraction.

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So, what’s next?

If you’ve tried adjusting dose, grind size, tamping, and distribution but are still facing issues, maybe it's time to reconsider your tools or even your coffee beans. High-quality beans and freshly roasted coffee can also significantly improve puck consistency. You might want to try our coffee blends sourced from local Australian roasters.

At Brewed Co Coffee, we’re always here to help—feel free to reach out via our contact page for personalised support.

Happy brewing!

Written By Laurie Nance

I'm the founder of Brewedco Coffee™, passionate about coffee, coffee tools, and helping others better understand how to utilize them. With years of experience in the coffee industry, I love sharing insights on brewing techniques, choosing the right equipment, and the science behind making the perfect cup.