P Patrick Cotter

Why is My Espresso Puck Soupy?

May 13, 2024 · educational · espresso · videos
Why is My Espresso Puck Soupy?

If you are new to brewing espresso at home you may have found that your pucks leave a little to be desired. We all want that fresh, cakey puck that ejects easily and cleanly into the knockbox, but that’s not always what you get. The good news is soupy pucks have some clear causes, and depending on your machine you might be able to fix them! Let’s talk about why this phenomenon occurs. 

What Causes Soupy Pucks?

Most midrange and up espresso machines have something called a 3-way solenoid valve. This is a valve that sucks up excess water in your espresso puck when you disengage the brew pump. The water is pulled up into the valve like a vacuum, then deposited into the drip tray below. This process helps deal with that extra layer of water that forms on top of the puck naturally when you halt the flow. Not all machines are equipped with a valve like this unfortunately, and will likely produce a soupier puck no matter what you do. It’s actually one reason many users eventually upgrade out of entry level machines.

When the solenoid valve has a hard time pulling the water out of the puck, it can lead to a messy, soupy portafilter. So what can you do to fix it?

Soupy Puck Remedies

When thinking about the vacuum action of the solenoid valve, it’s helpful to consider what causes difficulties in the brewing process as well. One key area is grind size. A finer grind leads to more resistance, and less flow of water back up and out of the puck, much like it slows down shot times when brewing. One method to alleviate soupy pucks is by taking your grind a bit coarser, allowing that water to flow a bit more freely. However, it’s important to note that this will also change the characteristics of your shot, so if you’re happy with the taste and shot times you’re currently getting, this may not be a great solution for you. 

Second, you’ll want to make sure that you use the correct portafilter basket for the shot you’re pulling. If you use a small, single shot basket it can lead to a lot of room between the coffee puck and the brew head. This makes it harder for the solenoid valve to pull water out of the puck. To fix this, make sure you use the right size portafilter basket, or up your dose to more properly fill out your basket (worst case you get more espresso!). 

Finally, you can get a puck screen! Puck screens are far from new, but seeing more use in home espresso recently. These handy accessories help to more evenly distribute water through the puck of coffee grounds. They also keep the water separate from the puck once pressure from the pump is disengaged. This then makes it much easier for your solenoid valve to pull the water back out. The best part? Puck screens are relatively cheap ways to manage this issue!

Hopefully these tips will help you to diagnose your soupy pucks. If you want some visual references for this piece, check out our YouTube video on the subject below!


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