The Secret to an Even Extraction: Espresso Distribution
You've ground the coffee, tamped it, locked in the portafilter, and you're ready to pull the perfect shot. With the press of a button the pump turns on and fills the room with its loud hum. The timer on the scale ticks by...four...five...six, and you anxiously await the drop down of the espresso from the bottomless portafilter, a picturesque display of deep, chocolatey browns and delicate tawnies.
And so it begins, the silky streams join together, flowing gracefully into your cup.
But wait...oh no…
Is that?
A spritz of coffee hits you between the eyes! Violent spraying erupts from the portafilter, leaving both you and the back of your drip tray a mess. You bend over and peer up at the portafilter only to witness unsightly gaps in the beautiful swirl of creamy espresso.
It is what you feared — channeling.
You cry out and shake your fists at the sky. The start of a new day instantly tarnished, leaving you with nothing but a mess to clean up and disappointment in your cup.
Channeling is a frequent problem that can occur for a number of reasons including over or under filling your basket, poor tamping, and the topic of this article — distribution. This can play a huge part in the quality of your shot, so we have taken a moment to break down the importance of it, the different methods that can be utilized, as well as a few products to make it a little easier.
What is distribution?
Distribution, a term often thrown around in conversations among coffee enthusiasts, has more than one meaning. In this case, we’re defining distribution as the process of evenly dispersing coffee grinds in the portafilter basket. By distributing the grinds evenly, you are ensuring there are no more, or less, fines and non-fines on either side of the puck. In doing so, there is no discrepancy in the density of either side of the puck, resulting in an even extraction.
Why does it matter?
To put it simply, it matters because no one wants an over or under extracted shot. If the grounds are inconsistent across the puck, there will be inconsistency in the extraction and you’ll be left with an undesirable shot that may be too bitter or too sour.
One way this happens is clumps in your grinds. When there are clumps present throughout the basket, the water will flow around the clumps rather than through, which will result in some grinds being over extracted and some being under extracted.
Another result of undistributed grounds is an unlevel tamp. The way the grinds fall into the basket can affect your tamp. If they are not distributed evenly, one side will be more dense and the water will favor the other side. Like with clumps, the denser side will not have contact with the water as much and will be left less extracted.
Distribution Techniques
Thankfully, there are certain techniques that can help with this issue. Talk to any barista and they have their own strategy. However, this is a great debate among the coffee community about which methods are effective and which are not. An article by Barista Hustle does a great job at breaking down the various methods.
- Stockfleth - leveling the grounds with your finger while rotating the portafilter
- Finger Swipe - leveling the top level of the grounds by swiping your finger straight across
- As is - Doing nothing to the grounds before tamping
- Hand/palm - Same concept as the finger swipe, but using your palm
- Distribution tool - using a tool like the chisel or wdt tool to distribute the grinds across the puck
Distribution Products
The purpose of the Pullman Chisel Distribution tool is to quickly and easily distribute coffee in the upper portion of your coffee puck. In doing so, you'll be left with a brew bed with fewer pockets of uneven densities, resulting in a more even extraction and a better tasting shot. It fits most commercial baskets and has an adjustable depth from 7mm to 14mm.
It should be noted that the Chisel is only effective in distributing grounds on the top layer of the basket, which is useful at creating an easier surface to tamp, but isn't as effective in breaking up clumps.
WDT Tool:
The WDT or Weiss Distribution Technique moves below the surface of the grounds to not only break apart the clumps with the use of the thin, wire prongs and steady stirring motion, but also creates a uniform distribution of grounds throughout the filter basket.
The drawback of this method is the possibility of creating a mess and stirring the grounds outside of the portafilter. This issue can be minimized with the help of a espresso dosing funnel.
Beyond grind and dose size, distribution plays an equally as important role when producing a uniform extraction. The more evenly distributed the grinds are, the more evenly extracted your shot will be — ultimately meaning it will be sweeter and brighter, and isn't that the goal? If you are interested in learning more about what goes into making great espresso check out our blog Getting Started with Espresso.
