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Bottomless Portafilter Spraying: Why It Happens and How To Fix It

Bottomless Portafilter Spraying: Why It Happens and How To Fix It

Coffee Tips Jan 15, 2024

If you are new to using a bottomless portafilter, then you are most likely to run into the issue of a spraying portafilter. It’s an inevitable part of the learning process, but a simple problem to fix.

In this post, I will explain why your bottomless portafilter is squirting the coffee instead of a smooth pour and what steps you can take to fix the problem.

Why Your Bottomless Portafilter Is Spraying

When using a bottomless portafilter, users may sometimes notice that coffee is spraying erratically instead of streaming smoothly into the cup.

Portafilter Spraying is known as Espresso Channeling, and it happens when the coffee grounds are either clumped or not tamped enough. So the water finds some empty ‘channels’ that it flows through and no resistance from the coffee puck, which causes the water to spurt out of these small channels.

What to look for when your portafilter is spraying coffee:

  • Distribution: Coffee grounds need to be distributed evenly across the basket. Clumping can cause water to channel through the puck unevenly.
  • Tamping Pressure: Uneven or insufficient tamping can create pockets of different densities in the coffee puck, leading to water channeling and spraying.
  • Dose: Too much or too little coffee in the basket can affect the puck’s resistance to water flow. An improper dose may result in channeling.
  • Basket & Portafilter Condition: Damaged baskets, or those with blocked holes, and dirty portafilters can disrupt the flow of water and cause spraying.

Here is a quick checklist for troubleshooting:

IssueChecklist Item
Grind Size1. Adjust the grinder for a finer or coarser grind as needed.
Dose2. Use a scale to ensure the correct amount of coffee.
Tamping3. Apply even and level pressure when tamping.
Distribution4. Use a distribution tool or technique to eliminate clumps.
Equipment5. Inspect and clean the basket and portafilter regularly.

Clumped Coffee Grounds Are The Biggest Cause of Espresso Channeling

Bottomless Portafilter Spraying: Why It Happens and How To Fix It

Tamping pressure and the leveling of coffee grounds are two important components to extracting a consistent shot of espresso without any channeling issues.

The first thing you want to make sure of BEFORE you tamp is that your ground coffee is not clumpy.

Espresso grounds are really fine, so they tend to clump up easily as they come out of the grinder. After getting rid of any clumps, you’ll want to make sure you have applied the right pressure by using a tamper.

Leveling Coffee Grounds

Bottomless Portafilter Spraying: Why It Happens and How To Fix It

Before tamping, ensure that coffee grounds are level in the portafilter. An uneven surface can lead to channeling, where water passes through the coffee unevenly, affecting the shot quality. To level the grounds:

  1. Distribute the grounds evenly by gently shaking the portafilter or using a distribution tool.
  2. Check that the grounds are flat and even before tamping.
  3. If not level, use a light tapping motion on the sides of the portafilter to adjust the grounds.

To get rid of any clumps in the grounds, using a WDT tool can help you easily break these clumps. Then, a distributor tool can help you create an even surface before you tamp the grounds.

Tip: espresso distributor tools are available in several sizes depending on the size of your portafilter.

If you have a DeLonghi espresso machine (Dedica, Stilosa, La Specialista), the portafilter size is 51mm. Refer to this post for Breville Portafilter size guide.

Tamp Pressure Consistency

When tamping, you have to aim for a consistent pressure each time, typically around 30 pounds of force. To achieve this, you can use a calibrated tamper that clicks at 30 pounds to eliminate guesswork (Select the right size for your portafilter). But that’s not necessary, any stainless steel tamper will do.

  • Stand directly over the portafilter to apply pressure straight down
  • Keep the elbow at a 90-degree angle
  • Apply pressure until the tamper reaches the click point (if using a calibrated tamper)
  • Practice repeatedly to develop muscle memory

Grind Size and Dosing

The performance of a bottomless portafilter is significantly influenced by grind size and distribution. An incorrect grind size can cause the coffee to spray, as extraction is uneven.

If you’ve ever used a pressurized portafilter before, you know that you can get away with a coffee grind that’s a bit coarser than it should be.

For a bottomless portafilter, the grind should be fine, anything else will cause you lots of issues. Because a bottomless portafilter has no other way to pressurize the coffee puck, it has to be by using fine ground coffee and good tamping pressure.

A fine grind ensures that water is evenly dispersed through the coffee, resulting in a smooth, even flow. If coffee is ground too coarse, water channels through the grounds, causing spraying and uneven extraction.

  • Fine: Ideal for espresso, creates resistance for water flow.
  • Coarse: Leads to under-extraction and channeling.

Using The Right Dose To Avoid Portafilter Spraying

A bottomless portafilter can hold between 18g to 22g of coffee, depending on its size (51mm, 54mm or 58mm).

While it’s recommended that you use the full amount a portafilter can take, you can under-dose your bottomless portafilter.

If you plan on using less than the recommended amount, you’ll have to do two things differently:

  • Make the grounds finer by a step or two.
  • Apply more tamping pressure.

When you are using less ground coffee in your bottomless portafilter, you are leaving some space between the brew head and the coffee bed. To make up for this space, your puck needs to be stronger so the water doesn’t flow too quickly through it.

Coffee Bean Freshness

The quality of espresso is profoundly affected by the freshness of coffee beans. Fresh beans produce a more consistent espresso shot, with a fuller flavor and better crema. When beans are old or stale, they often lead to uneven extraction that can cause channeling, where water finds the path of least resistance, resulting in bottomless portafilter spraying.

Factors Influencing Freshness:

  • Packaging: Fresh beans should be stored in airtight containers with one-way valves to allow gases to escape while preventing air from entering.
  • Roasting Date: Coffee beans reach their peak flavor within a few days to a couple of weeks after roasting.
  • Grind Size: Freshly ground beans ensure that the coffee’s volatile aromatics and oils are preserved, leading to a more flavorful shot.

Storage Recommendations:

  • Temperature: Keep beans in a cool, dark place.
  • Avoid Moisture: Coffee should be kept away from moisture to preserve its quality.
  • Limit Air Exposure: Limit the time beans are exposed to air by keeping them sealed.

Espresso enthusiasts should note that consistency in tamping and grind size in conjunction with fresh beans will significantly reduce the occurrence of spraying from a bottomless portafilter. Hence, selecting and maintaining the freshness of coffee beans is a critical step for a perfect espresso shot.