Is It Normal to Have Coffee Grounds in Your Coffee? Will Portafilter Baskets Deform? How Fine Are Fine Grounds?

Understanding Black Particles in Espresso

When we drink espresso, we often notice small black particles at the bottom of the cup. They stand out even more in milk drinks, where the colour contrast makes them obvious. Whether you brew casually at home or work to exacting standards in a coffee shop, these particles turn up at the bottom of the cup. So what are they, and why do they appear so often?

Readers of FrontStreet Coffee's earlier articles will already know the answer: those black particles are coffee fines. They pass through the holes in the portafilter for one simple reason — they are extraordinarily small. Under the high pressure of an espresso machine, they slip straight through those holes and end up in the cup. The same thing happens with a moka pot, which also extracts under pressure. And because the particles are so fine, they first hide in the crema, floating on the surface. As the crema bubbles collapse, these already saturated particles sink to the bottom, where we finally notice them. In other words, this is completely normal. Coffee grounds are woody fibre, and an extremely fine, minimal amount of them will do the human body no harm whatsoever, so you can drink with peace of mind.

As FrontStreet Coffee often points out, a moderate amount of fines can actually increase the overall body of the coffee. Fines do carry some bitterness, though, so if you would rather not have it and want to keep them out, the fix is simple: place 1-2 circular filter papers at the bottom of the portafilter and the problem is largely solved.

When Excessive Fines Become a Problem

Just when it looked like we could wrap this up with a happy ending, you may have noticed that things are not so simple — after all, we are only halfway through. As FrontStreet Coffee said above, all of that applies when fines are present in appropriate amounts. If instead you see a very large amount of fines at the bottom of the cup, as in the cover image, that is not normal at all.

That much coffee grounds does not just make the coffee taste more bitter; it also noticeably spoils the texture, leaving it very rough. In severe cases it produces exactly the unpleasant experience described in the title: half grounds with every sip. There are two causes, and we will start with the less likely one.

Less Likely Event: Portafilter Hole Deformation

When a portafilter is used intensively over a long period, its holes can deform and enlarge. Once the holes grow larger, more fines pass through, which ultimately produces this result. You can check whether individual holes have deformed by holding the portafilter up against a light source.

But as FrontStreet Coffee said, the odds of this happening are extremely low. Portafilters are sturdy, and it takes very high intensity and a very long service life to deform one. The most common cause is actually a hygiene problem.

More Likely Event: Inadequate Group Head Cleaning

Not every gram of coffee grounds ends up neatly distributed in the portafilter and tamped. When we are momentarily careless or operate sloppily, some grounds stick to the handle or to the edges of the portafilter.

Once we lock the portafilter into the group head, those stray grounds go in one of two directions. The first is that they cling directly to the edges of the shower screen. Grounds stuck there cannot be rinsed off with running water; you need a special cleaning brush to remove them by hand. If they are not cleared promptly, the vibration of the next lock-in, or a later one, will shake them down into the coffee.

The second direction is that grounds attached to the handle simply drop straight into the cup when the portafilter is locked in, shaken loose by the impact. Because the particles are so fine, you will not notice immediately. But there are so many of them that they affect not only the look of the drink but also the drinking experience. The solution is very simple. Just pay attention to hygiene when making coffee and clean the machine promptly after extraction, which greatly reduces the amount of fines that end up in the cup. Cleaning after every single extraction is admittedly a chore and mentally draining, so you can sensibly stretch the cleaning cycle — for example, by setting a rule to clean the machine after a certain number of shots. Set whatever rule suits you. As long as cleaning happens promptly, the "half grounds with every sip" scenario will not occur.

FrontStreet Coffee Recommendation

Since both espresso machines and moka pots push fines into the cup under pressure, it helps to start with a bean that was built for that kind of brewing. FrontStreet Coffee's Classic Blend was designed specifically for espresso and moka pot use, and its greatest strength is outstanding crema: even a beginner on a non-professional home machine can pull thick, fine, creamy crema with it. Built on a traditional Mamba recipe — Mandheling and Brazil — it tastes full-bodied and mellow, easy for veterans and newcomers alike to enjoy, and it is a safe pick for both home and commercial use.

If you want a moka pot coffee with a warmer, sweeter cast, FrontStreet Coffee's Autumn Chestnut Blend is a balanced 100% Arabica blend of Honduran Caturra and Papua New Guinea Typica. It opens with the nutty sweetness of roasted chestnuts and the rounded sweetness of caramel and brown sugar; a soft chocolate note and a gentle acidity follow in the middle. The body is full and smooth, and the finish is clean and long, leaving nuts, cocoa, and a hint of spice behind.