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How to Banish Uneven Extractions
Step by Step
Make a funnel by cutting out the bottom of a yogurt container so that
it wedges neatly in the top of your filter basket. This allows you to
stir as vigorously as necessary without grounds spilling everywhere. If
your grinder's clearance allows it, grind directly into the
funnel/basket/portafilter combo until you have a slight mound of coffee
grounds. Otherwise there are a couple of other options:
- Grind into a container and then transfer the grounds into the
- Grind directly into the portafilter as with standard volumetric
dosing, and then insert the funnel.
If you prefer, weigh the grounds first, but I like to dose strictly
by volume. As usual, the grind setting should be adjusted to achieve a
25-30 second espresso pour. The pictures below summarize these first
Stir the grounds in the funnel/filter basket with a needle. The
stirring pattern does not seem particularly important. Some baristas
prefer a circular pattern, whereas I simply stir vigorously back and
forth. Any stirring pattern works, as long as it breaks up clumps and
achieves a uniform distribution of coffee grounds throughout the filter
The dose should be adjusted for optimal results with different
coffees, grind settings, filter baskets, and brewing conditions. For a
richer, more ristretto-like extraction, try packing a bit more coffee grounds in the filter
basket. However, if the top of the puck touches the shower screen as you
lock the portafilter into the group head, you have overdosed the basket.
Contact between the puck and the shower screen before the shot may
disturb the integrity of the puck and break the puck / filter basket
adhesion, which leads to uneven extractions. If you feel resistance as
you lock in, reduce the dose.
The WDT allows you to adjust the dose by volume in several ways:
- how vigorously you stir the grounds with the needle,
- gently tapping downwards on the counter to settle the grounds
- how you level the grounds.
With a little practice, dosing becomes quite easy. The key point to
remember is consistency in the method you choose. The photos below
summarize these steps.
Vigorous stirring fluffs up the grounds so that less coffee fits in
the filter basket, and allows you to correct overdosing errors. To
reduce the dose (downdose), stir the grounds and level with a straight
edge without any downward compression. I like to sweep the
grounds back and forth in an "X" pattern with the dissecting needle
handle, but you can use a knife blade, ruler, or your finger.
To increase the dose (updose), tap downwards a couple of times on the
counter before leveling. Alternatively, compress the grounds using Schomer's
finger compression approach, Stockfleth's move, or the Chicago Chop as you
level. The dissecting needle handle again makes a convenient tool when
performing the Chicago Chop (named after the technique employed by the
baristas at Intelligentsia Coffee). This downward "chop chop chop"
motion across the top of the filter basket with the handle gently and
uniformly compresses the grounds; follow the chopping motion with a
quick level by sweeping back and forth.
Leveling the grounds provides a uniform surface for tamping, and
makes dosing more dependable. Regardless of your technique (Schomer's,
Stockfleths, Chicago Chop, straight edge), I recommend leveling to the
top of the filter basket for greatest consistency in dosing.
When using this method for the first time, try a simple direct
tamping style. Tamp once with medium pressure, with an emphasis on
keeping the tamp centered and level. Brush off the basket rim and invert
the portafilter briefly to discard any stray grounds. Then tamp firmly
(using at least 30 pounds pressure) and finish with a no-pressure
polishing twist. A convex tamper base is more forgiving in my hands, but
some prefer a flat tamper base. The photos below summarize these steps.
Other tamp styles also work well (such as the Staub NSEW approach).
In general, an even distribution permits any reasonable tamping style,
whereas no tamp can cure an uneven distribution. Tamp styles that
involve tapping the side of the portafilter, however, can disturb the
integrity of the puck, and are not recommended.
Now it's time to lock in and pull your shot. If you're using a
bottomless portafilter (highly recommended!), a uniform pattern of
initial beads is indicative of a promising pull. Multiple streams should
rapidly merge into a single, centered, beautifully tiger-striped stream
of espresso goodness. Be sure to stop the pour at the first signs of
blonding. Then sit back and enjoy your well-deserved reward!
Uniform start promises
an even extraction.
This was a good pour.
Is the WDT right for you?
Although I believe the WDT can improve everyone's espresso pours,
some will clearly benefit more than others from this technique. Stirring
the grounds only affects dose and distribution, and will not cure
problems associated with stale beans, poor grind, incorrect brew
temperature, and so on. It is less likely to help those who:
- work in a high volume coffee establishment, where commercial
grinders function well and speed is essential;
- already have achieved a high degree of skill and consistency in
their espresso extractions by developing their own methods to overcome
grinder design inadequacies;
- have a grinder (such as the Versalab M3) that distributes grounds
- have especially forgiving brewing equipment, such as espresso
machines with the preinfusing E61 group.
People who will likely benefit most from the WDT include those who:
- see obvious clumping and uneven distribution from their grinder;
- have less forgiving espresso brewing equipment;
- see uneven espresso extractions from their bottomless portafilters;
- are starting on their journey into the world of espresso.
But even the experienced barista may find the WDT improves his/her
pours. Below is a testimonial from Jon Rosenthal, master of the naked triple ristretto:
"John, I'd like to thank you for sharing your technique (and
for sending me the 'WDT tool' dissection needles). I now use a needle to
stir the basket on every shot and my consistency has definitely
improved. This technique may not be sensible for a commercial setting,
but in the world of the Home-Barista, this technique will surely help
many people get better extractions."
And HB's own Dan Kehn comments "This is the best 'newbie
cheat' that I've tried."
The WDT puts the focus on distribution, a critically important and
oft-neglected part of espresso technique. Call it a crutch, call it a
cheat, call it whatever you will, but I have not found anything else
that approaches the consistency and flexibility of this approach. Give
it a try and see for yourself. If possible, use a bottomless
portafilter— it's one of the best available tools for diagnosing
your pours. With good distribution, you will bang out one
espressoporn-worthy shot after another.
But don't take my word for it. Examine the videos below and see for yourself.
Acknowledgements & References
Many thanks to Dan Kehn, Jon Rosenthal, and others for their
encouragement, support, and willingness to try something new. And a
special thanks to Mark Podolsky, who originally dubbed this method
"the WDT." Below are a few of my favorite online references
related to improving the quality of espresso extractions.
Perfecting the Naked Extraction
"It's tempting to blame an uneven extraction on an
inconsistent tamp, but in the majority of cases, improper distribution
is at fault... I prefer to overdose the basket slightly differently than
the steps described by David Schomer. Instead of overdosing by
compression strokes, I gently tap the portafilter on the grinder fork
twice when the basket it about ¾ full, and then finishing
filling. Finally I do four leveling drags South-North, North-South,
West-East, and East-West without compression."
Espresso Packing Techniques: Update 2004
David Schomer updates his packing and distribution
technique, reminding us that "...a master barista doing the dance of
espresso preparation is beautiful to watch. A fluid packing technique is
the heart of the whole thing and adds to the romance of this little thin
sweet coffee prepared especially for you."
Stockfleths move video
Tim Wendelboe demonstrates the rotational distribution
technique for preparing espresso.
Schulman's summary of leveling techniques
"There's two, maybe three, leveling styles:
- with the tamper. Either NSEW tamps (also
known as the Staub tamp for its inventor, although Schomer seems to be
claiming credit all of a sudden). Or a nutating motion, like a coin
settling after its been flipped; this is my favorite, since it's very
- with the hand, Stockfleths move. Hold the
portafilter and your other hand at your chest. Turn out your elbows.
Put the fat part of the palm (at the end of the thumb) of your empty
hand on top of the grounds, gently. Turn your elbows in. The 180 degree
rotation levels the grounds. This move is also very fast, since it can
be performed as you remove the portafilter from the grinder.
- I saw the Italian barista at the SCAA, I
keep forgetting his name, get perfect shots by simply doing a swirling
motion on the portafilter without any tamp. I assume this takes a lot
of practice and muscle memory, so I haven't experimented.
The pull will always start with separate drops appearing,
ideally completely uniform across the whole basket surface. Spritzes
show pinhole faults in the puck. They are far less serious than visibly
uneven flow from the basket (i.e. flowing from one half but not the
other) since they repair themselves. Nevertheless, they show the
levelling was not perfect. The major change most people who were
relatively painstaking make is not to tap, beat or knock the basket,
especially after levelling and before tamping. The other major change is
that tamping becomes far less important than levelling. You can get a
perfect naked shot without tamping, providing the levelling was perfect;
but no tamp on earth will save a poorly levelled basket."