Coffee Facts

Why Is the Espresso Puck Stuck to the Group Head?

Is your espresso puck stuck to the group head screen and you don’t know why or how to fix it? We will explain why and how to avoid this problem in the article below.

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Getting the perfect espresso machine for your preferences takes some trial and error, and sometimes even the best espresso machines will do something unexpected that isn’t addressed in the manual. For instance, what if your espresso puck gets stuck?

An espresso puck is the clump of used grinds you get after pulling your espresso shot. Ideally, your puck should be very compact, hot, damp, and easy to knock out of the portafilter with a knock box.

Sometimes, though, your puck will be too wet, while other times it might suction and stick to the group head screen rather than coming off in the portafilter.

Not only is this annoying, but it can be messy and frustrating to clean up if not removed properly. But don’t worry, we explain why this happens, how to avoid getting it over and over again, and the best techniques for cleaning it!

espresso puck stuck to group head

Why Does My Puck Stick to the Grouphead?

More often than not, having your grinds stick to your group head is caused by having too much coffee grounds in your portafilter.

Coffee grounds expand with the pressurized hot water that is poured through them during brewing. So, if your portafilter is overpacked, this will cause the puck to suction up to the screen, coming out of the portafilter when it’s removed.

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It’s common for this to happen when you’re dialing in a new roast or if you’re not dosing out your shots correctly. Grinders with preset dosages are great, but not always 100% accurate as they are timer-based, not weight-based. 

Therefore, make sure you’re following the appropriate espresso ratio to know the best weight for your ideal brew. 

Another reason your puck may be sticking is a lack of effective tamping. Having an uneven surface can cause channeling in ways that make your puck stick to the group head, either partially or fully. 

If the screen of your group head isn’t properly maintained and cleaned regularly, a build-up of coffee oils on the screen could also contribute to the blockage. 

Another cause, albeit less common, for stuck coffee grounds could be environmental factors, such as a sudden change in biometric pressure or humidity. 

Techniques For Easy Clean Up 

It’s actually fairly easy to clean up your coffee puck efficiently and mess-free. The easiest method is to use the portafilter to knock it off into the basket.

This can be done by putting the portafilter back up near the group head, but not locking it back into place.  Simply line it up with the stuck espresso powder, and then scrape it off using the portafilter.

Another option is to simply use a paper towel, cupping the puck with the towel in your hand and knocking it off gently with pressure from your fingers.

If the puck is still hot, you will feel it through the towel, so be careful to avoid burning or hurting yourself. 

If you’d rather avoid touching the stuck grounds, simply run the shower screen without the portafilter attached and the puck will fall off.  This will make a bit of a mess and the grinds will be hot to the touch at first, but it will get them down easily enough.

How to Avoid a Stuck Puck

If the puck sticks only after one shot, you may have just experienced a fluke, such as a change in environment. However, if the coffee grounds continue to get stuck, especially from one particular roast, you’ll want to figure out what’s going on and why.

The easiest and fastest way to ensure this isn’t a recurring problem is to simply weigh out each dose before brewing. You can do this using a single-dose method before grinding, or you can simply weigh your grinder dose once it’s in the portafilter.

To weigh grinds in a portafilter, you’ll need to take out the weight of the portafilter on a coffee scale, then weigh again once the grinds are situated. This way you can ensure you’re getting the exact right dose. 

Be sure to use an appropriately sized basket for your portafilter as well, weighing out a double shot into a 20g basket and not a single-serve basket.

No matter the size of the basket, your grinds should be below the edge of the portafilter.  If grinds are up to the brim, you’ve packed it too full and will not get a great shot. 

If your dose is an accurate weight and you’re using the correct portafilter size, but continue to experience a stuck puck, you’ll want to try cleaning the group head shower screen. 

Ideally, this should be cleaned very regularly and rinsed with a back flush after every use.  Otherwise, the coffee oils and residue will build up, creating blocks within the screen and affecting the quality of your espresso in the process.

If, after all of these methods, you’re still experiencing stuck coffee grounds, then you may need to redial your espresso to be a coarser grind and use less weight and pressure when tamping. 

In Conclusion  

 A stuck puck can be annoying, but it doesn’t need to be messy and can be fixed with some minor tweaking if it’s a continued problem. 

However, simply having a stuck puck doesn’t mean your espresso shot is a waste. I’ve pulled many good shots that ended up being stuck to the group head but still tasted great.  

Maintaining and cleaning your grinder and espresso machine is key for continued smooth operations and will help prevent problems, but with these easy tips and tricks, you can figure out what else may need to be adjusted for a continued stuck puck!

Happy Caffeinating!

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