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

Published: 2026-01-27 Author: FrontStreet Coffee

Last Updated: 2026/01/27, When we drink espresso, we often notice some black particles at the bottom of the cup, especially in milk-based coffee drinks where these black specks are more conspicuous due to color contrast. Whether it's casual home brewing or professional coffee shop preparation, these particles tend to appear consistently

Understanding Black Particles in Espresso Coffee

When we drink espresso, we often notice some black particles at the bottom of the cup, especially in milk coffee with added milk, where these black particles become more visible due to the color contrast. Whether it's casual home brewing or precise processing in coffee shops, these particles always appear at the bottom of the cup. This naturally makes us curious: what exactly are these particles, and why do they frequently appear in coffee?

Actually, friends who have read FrontStreet Coffee's previous articles know that these black particles are actually coffee fines. The reason they can pass through the holes in the portafilter is simply because their size is incredibly small! Under the high pressure of the espresso machine, they can directly pass through these holes and join the coffee. Similar situations occur with moka pots, which also use pressure-based extraction. Moreover, because these particles are extremely fine, they initially hide in the crema, floating on the surface of the coffee. As the crema bubbles break, these already saturated particles fall to the bottom of the cup where we notice them. Therefore, this situation is completely normal! Although coffee grounds are woody fibers, extremely fine and minimal amounts of them will not have any adverse effects on the human body, so you can drink with peace of mind.

Furthermore, as FrontStreet Coffee often says, an appropriate amount of fines can increase the overall body of the coffee. Of course, fines come with some bitterness, so if we don't want this bitterness and wish to remove the fines, it's very simple. Just add 1-2 circular filter papers at the bottom of the portafilter, and you can minimize this problem!

When Excessive Fines Become a Problem

Just when we were about to conclude with a happy ending, I believe everyone has noticed that things are not that simple. After all, we're only halfway through the progress bar! FrontStreet Coffee mentioned above that this applies when fines are "present in appropriate amounts." However, if we see a very large amount of fines at the bottom of the cup, as shown in the cover image, then this is not a normal phenomenon!

Such a large amount of coffee grounds not only makes the coffee taste more bitter but also significantly affects the overall texture, making it very rough! In severe cases, it leads to the unpleasant experience mentioned in the title: half grounds with every sip of coffee. There are two reasons for this situation, let's first discuss the less likely one.

Less Likely Event: Portafilter Hole Deformation

When a portafilter is used intensively for a long time, it can easily lead to deformation and enlargement of the holes. When the portafilter holes become larger, more fines can pass through, ultimately leading to this phenomenon. We can check if individual holes are deformed by holding the portafilter against a light source.

Checking portafilter holes against light

But as FrontStreet Coffee mentioned, the probability of this happening is extremely low! After all, portafilters are very sturdy and require very high intensity and very long usage time to deform. The most common reason is actually hygiene issues!

More Likely Event: Inadequate Group Head Cleaning

Not all coffee grounds will be neatly distributed into the portafilter and tamped by us. When we're momentarily careless or operate improperly, some coffee grounds will stick to the handle or the edges of the portafilter!

These coffee grounds will take two directions after we lock the portafilter into the group head. One is to directly adhere to the edges of the shower screen! When coffee grounds stick to the edges of the shower screen, we cannot rinse them off by running water, but need to use a special cleaning brush to manually remove them. If not removed promptly, these coffee grounds will fall into the coffee during the next or subsequent locking of the portafilter due to the vibration from the impact!

The other direction is that when locking the portafilter, these coffee grounds attached to the handle will directly fall into the cup due to the vibration from the locking action! Because the particles are extremely fine, they won't be noticed immediately. However, due to their excessive quantity, they not only affect the appearance but also diminish the coffee drinking experience. The solution to these situations is very simple! We just need to pay attention to hygiene when making coffee and clean the coffee machine promptly after extraction, which can significantly reduce the amount of fines falling into the cup! Of course, cleaning after every extraction is very troublesome and mentally taxing, so we can appropriately extend the "cycle" of cleaning, for example, setting rules like cleaning the coffee machine after a certain number of extractions. You can set your own rules anyway. As long as cleaning is done promptly, the situation of "half grounds with every sip of coffee" won't occur~