You know those times when you go to make espresso and water just starts shooting out of the portafilter instead of going through the coffee? Yeah, that’s called channeling and it’s the bane of every espresso lover's existence. Channeling makes for a less than satisfactory espresso. So, what is this phenomenon and how do we prevent it?
What is Espresso Channeling?
Espresso channeling is when water finds a small path instead of flowing through the entire coffee puck evenly. When water finds a weak point in the puck, it will start eroding the bed and create a channel. That path will have less resistance and let more water through making an uneven flow.
As a result, the coffee extracted near the channel will be over-extracted and the rest of the puck will be under-extracted. This results in espresso with an uneven flavor profile with the shot being acidic and bitter at the same time.
Signs of Coffee Channeling
The most obvious sign of coffee channeling is, of course, water shooting out of your basket. You will need a naked portafilter to see the spurting. There are other tell signs to look out for, too. If your shots are coming out watery, weak, and astringent that’s another indicator that your coffee is channeling. It can also be both acidic and bitter at the same time.
Causes of channeling
Now that you know how to spot channeling, let’s talk about what causes it. There are three main causes of channeling: grind size, coffee distribution, and tamping.
Grind too fine
One of the most common causes of channeling is grinding your coffee too fine. When the grind is too fine, water has a harder time flowing through the coffee bed and can start to seep through cracks and crevasses, resulting in channeling.
Poor Coffee Distribution
Another common cause of channeling is poor coffee distribution. When you don’t evenly distribute your coffee in the portafilter basket, water can flow through the path of least resistance, resulting in channels forming in the coffee bed. You can easily fix it with a WDT tool!
Uneven Tamping
The final cause of channeling is an uneven tamp. If you don’t tamp down your coffee evenly, water will again flow through the path of least resistance, resulting in…you guessed it…channels!
Impact on Extraction
Channeling has a big impact on espresso extraction. When espresso is channeling, it can cause the coffee to over-extract in some areas and under-extract in others. This results in an espresso with an uneven flavor profile that can be both acidic and bitter at the same time.
How To Prevent Channeling
Now, let’s talk about how to prevent it. The best way to prevent this phenomenon is by ensuring an even grind size, distributing your coffee evenly in the portafilter basket, and tamping down with even pressure. We have a WDT tool available and a more conventional distributor.
Simulations advocate for the fastest flow, to reduce channeling. It might be tempting you to apply 15 bars of pressure on your espresso however, the would lead to rapid coffee bed erosion and channeling, making for an overly astringent espresso.
You don’t want to clog your espresso, but you also don’t want to destroy your coffee puck by eroding it with a very large flow and pressure This necessitates careful puck preparation to enhance the coffee bed's structural resilience against erosion.
Check out our blog post on how to make espresso for more tips on making the perfect shot!
So there you have it! Now you know all about channeling in espresso and how to prevent it. Remember to use an even grind size, distribute your coffee evenly in the portafilter basket, and tamp down with even pressure for perfect shots every time. So next time you're making coffee at home, remember these tips and enjoy a delicious, flavorful cup of espresso without any channels!
