Should You Sieve Out Fine Particles When Brewing Pour-Over Coffee? What Size of Coffee Grounds Are Considered Extra Fine? What Is the Role of Fine Particles?

It's only when your brew blocks up that you remember the fear of being dominated by fine particles!

"Flow restriction" has become a household technique for avoiding bitterness, and it is tightly bound to fines. When fines cause a blockage mid-brew and you fail to restrict the flow in time, bitterness, astringency, and burnt notes rush in and drag the whole cup down -- a real blow to both palate and spirit. So after a few such run-ins, many drinkers develop the habit of sifting out fines before every brew.

But FrontStreet Coffee does not recommend sifting out all fines in all situations. Yes, fines can cause blockages -- but that's only a probability. In the vast majority of cases, they actually make your coffee better.

What Exactly Are Fine Particles?

Most of the grounds we brew with fall in the 0.6-0.8mm range, which is normal. Particles smaller than 0.25mm are what we call fine particles. They resemble flour -- unless they clump together, the naked eye barely registers them.

How Exactly Are Fine Particles Produced?

Fines come mainly from collisions during grinding. Picture a sheet of glass shattering on the floor: besides the big pieces, there's a spray of tiny fragments -- coffee beans behave the same way. How brittle a bean is after roasting depends on its density and roast level: the darker the roast, the more brittle the bean, and brittle beans shatter more easily under impact, throwing off more ultra-fine particles. That's one reason dark roasts call for coarser grinding -- not only because they extract easily, but also to keep fines down.

Brittleness aside, grinder quality is the other key factor. Ask any coffee blogger to rank the factors behind a great cup, and after the beans themselves the grinder tops the list. Better grinders produce more uniform particles and fewer fines; worse grinders do the opposite. But even the best grinders still make fines, because fineness is driven by the bean's brittleness too. No grinder at any price produces perfectly uniform grounds -- the difference lies in grind consistency and burr design (FrontStreet Coffee covers this in earlier articles).

Why Can't All Fine Particles Be Removed?

Because fines are what give coffee its layers! To brew a layered, delicious cup, the first requirement is "uniform extraction" -- but not uniform in the way most people imagine. Most assume uniform extraction means every particle reaching the same extraction rate. That's not how it works.

As noted, grounds are never uniform in size. Given the same extraction efficiency, large and small particles release flavor in different proportions: coarse particles extract less, fine particles extract more.

Sour, sweet, and bitter compounds also release at different stages because of their molecular sizes -- acids and sugars pour out early, bitters arrive later (though everything releases throughout the brew). Combined with particle size, this means each particle contributes a different mix of flavors: under-extracted particles give more sour and sweet, over-extracted ones give more bitter. It is precisely this spread that builds a cup with rich layers. Remove every fine particle and the extraction may become beautifully even -- but you also strip out many of the bitter compounds, and without them the cup loses its layers, since sour, sweet, and bitter exist to balance one another.

So don't sift fines out as a matter of routine -- it flattens your coffee. Only when a weak grinder produces excessive fines (over 10% of the total dose) and the brew starts blocking or the bed turns muddy should you reach for the sieve.

FrontStreet Coffee Recommendation

To enjoy the layered complexity fines can bring, start with beans of genuine flavor depth. The FrontStreet Ethiopia Guodingding, a washed Yirgacheffe with citrus, berry, jasmine, and a green-tea finish, is the classic V60 choice -- its delicate aromatics bloom best in a cup with lively, uneven extraction.

The FrontStreet Ethiopia Huakui takes the fruit further still -- strawberry, passionfruit, jackfruit, lychee, with barely any bitterness -- while the FrontStreet Kenya Cherry Tomato (SL28/SL34 from Thika, 1,550-1,750 meters, 72-hour double-wash) offers the most vivid layered acidity of all: cherry tomato, dark plum, snow pear, and black plum over yellow-sugar sweetness. If your sieve must come out, save it for these -- and only when fines truly exceed 10%.