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There is only one thing every espresso expert agrees on: The grinder
is the single most important piece of coffee equipment you'll buy, and
the last place you'd want to skimp. This has a simple reason—the
coffee grind is both the most critical and the weakest link in espresso
making. It is critical, since unlike regular brewing, the grinder
adjustment determines both the espresso's extraction rate and it's
brewing time. The grinder is the weakest link because ground coffee is
anything but uniform.
When brewing, there's two time factors—the amount of time the
coffee should brew, and the amount of time it does
brew. The grind fineness determines how long it should brew—the
finer the grind, the faster the proper brew time. Less brew time is
better when the grind is finer because more surface area is in contact
with the water and the coffee solubles dissolve more quickly. But for
most brewing methods, the amount of time it does brew is determined by
you since you can choose to pour through the filter faster or slower,
let the French press brew longer or shorter, etc. This means for
non-espresso preparation, you can stick to one grind and pick a brewing
time to match.
In espresso, the grind fineness also determines the brewing time, but
does so in the opposite direction from the time it should brew. The
finer the grind, the more the coffee puck resists the flow, and the
longer it takes to brew the same amount of espresso. But the finer the
grind, the quicker the coffee solubles extract. In other words, there is
only one correct grind setting that gets just the correct timing, and
even small deviations screws it up, giving you either an over or
underextracted espresso. In practice, good baristas will frequently make
minute adjustments to the grind to keep it at the sweet spot as beans
age, and ambient conditions change.
Experience shows that the correct timing for espresso is brewing one
ounce singles or two ounce doubles in about 25 to 30 seconds; grind
fineness should be selected to produce this volume in this time. There
are a few things the barista can do to compensate for a slightly off
grind, which I'll discuss later in the Mano section. But these tricks
are limited; in practice one needs a grinder with lots of available
Many home grinders only have 10 to 20 settings over the entire range
from fine to coarse. This translates to about 2 to 4 settings in the
espresso range, which is not enough to get the grind right. An espresso
grinder either needs a stepless adjustment, or at least 40 settings over
the entire range in order to work well.
In theory, if all the ground coffee had the same particle size, it
would all brew at the same rate and you could get a perfect extraction.
If the grind size is not uniform, the smaller particles overextract, the
larger ones underextract, and the result is less than perfect.
Unfortunately, coffee is brittle and shatters as it is ground. So even
the best contemporary grinders produce a wide distribution of particle
sizes. Moreover, some size variation is required for the mechanics of
the espresso puck. If all the particles had the same size, there would
be large gaps in the coffee puck, and the pressurized water would gush
through. A wide distribution of sizes creates a dense pack that resists
the flow and allows proper extraction. This is probably the reason why
high grown coffees don't do well as espresso since their fines
(smallest, dust like grind particles) create a very acrid taste.
The very best grinders are commercial conical burr grinders. These
produce elongated particles which pack well, and fewer fines. They are
currently very expensive and beyond the reach of almost all home
Commercial flat burr grinders are nearly as good, although they
produce slightly more fines and a more metallic taste with high grown
coffees. However, smaller models are only one-third to one-quarter the
price of commercial conical burr grinders, and they include some
packaged specifically for home use. These run from about $250 to $500
and are recommended for anybody serious about espresso.
Mazzer flat burrs - note
sharp deep ridges
Fake flat burrs - knobs
There are several manufacturers of home conical grinders. These
models work very well for brewed coffee, and some models have enough
grind settings to work fairly well for espresso. However, the taste
won't be as good as a commercial grinder's. They have lower power
motors, plastic gears and lighter duty burr mounts; so the burrs wobble
and vary in speed slightly during the grind. Espresso particle size is
measured in the 1/1000ths of inches, so even a little wobble and speed
change degrades grind quality. Nonetheless, such grinders are a decent
economy choice and cost around $150.
Solis conical burrs mounted
on soft plastic
Innova conical burrs mounted
on hard resin
Finally there are contraptions falsely called burr grinders that cost
around $50. These are not actually burr grinders, but use knobs to crush
the beans. Since this produces a large quantity of fines, they will
produce an acrid shot with even the most mild mannered all-Brasil
blends. They are to be strictly avoided for any coffee use. Whirling
blade grinders (that look like tiny blenders or food processors) are
also to be avoided, since they too produce excessive dust.
There are non-coffee factors to grinder design that affect their
cost. In general, grinders which do a good job but are less expensive
tend to be slower, noisier, and messier. It is up to each person to
weigh their priorities in economy versus lack of annoyances.
It seems fairly clear to me that any fundamental innovation in
espresso will require improvements in grinding coffee. However, the
problems are great, so this is an area where technology moves slowly. In
the mean time, the existing technological deficiencies in grinder design
means that one has to buy the best grinder possible to get decent
Next page: Espresso machines...