Tamping is a crucial step in the coffee-making process, involving precisely pressing coffee in the filter holder basket. Correct tamping aims to ensure a uniform flow of water through the coffee grounds, which is indispensable for achieving the best flavor in your coffee.
Why correct tamping is vital for espresso extraction
When extracting espresso coffee (even with a manual machine), it is very important to tamp it correctly for two fundamental reasons:
- We create a resistance to the passage of water during extraction, increasing the pressure up to 9 bars.
- We create a uniform space between the coffee and the group of coffee makers. This space is filled with water, and as the pressure increases, the water descends in the form of a column, thus achieving a uniform extraction.
Choosing the right size tamper
When tamping the coffee in the portafilter basket, the first essential tool you’ll need is a tamper. It’s important to note that not all baskets have the same size, and correspondingly, not all tampers will be the same size either. Hence, to achieve optimal results, it is necessary to use a tamper that matches the size of the basket being used.
If we are talking about commercial espresso machines used in coffee shops, these have filter holders with 58mm baskets. However, domestic coffee makers use slightly smaller baskets, with 57mm being the most common. But in smaller coffee makers, we can see baskets of even 46mm.
The importance of a flat base tamper
I still don’t understand why there are tampers with a convex base because when you tamp, the coffee puck is not flat but with a depression in the center.
Consequently, when brewing coffee this way, the ground coffee in the center is usually over-extracted while the coffee in the periphery is under-extracted, resulting in a poor-quality espresso.
Avoid plastic tampers for better results
Many domestic espresso machines have a plastic tamper among their components. As they are very light, they are also very unstable, making it very difficult to get the right pressure and leveling.
When you put pressure on one of these plastic tampers, they move and bend, producing uneven and uneven pressure. A stainless steel tamper is not too expensive and is a safe investment for quality espresso.
Choosing the best tamper for preparing espressos
There are many types of tampers with different shapes, designs, and materials. And this is fine since every barista has their style, and not all of them will be ideal for every person.
I recommend looking for a traditional tamper with a stainless steel base and wooden handle. As for the shape, the classics are still a safe bet. In the image below, you can see the one I use.
Step-by-step guide: How to tamp coffee correctly
The tips I will give you below may vary from those you may have seen in other articles or online videos. But probably all of them are correct; each barista has their technique, and based on it, they will advise you differently.
Step 1: Add the coffee to the basket evenly. You can help yourself with your fingers but never tamp with them.
Step 2: Now hold the tamper with your hand as if you were going to hold a flashlight, leaving your thumb and index finger on the edge of the tamper to feel the contact with the filter holder basket. See my hand in the next image.
Step 3: Rest the filter holder on a flat, straight surface with your left hand (if you are right-handed), and position your right arm vertically over the filter holder basket with the tamper in your hand. The elbow should form a 90-degree angle.
Step 4: Now apply enough force on the coffee until it no longer goes down, without adding more pressure than necessary. With this pressure, you will have removed all the air between the ground coffee. Turn slightly with your fingers in contact with the edge of the filter holder to ensure it is level.
Be careful not to exert uneven pressure, as the coffee puck will not be horizontal, resulting in an irregular extraction. This problem is called “channeling” because over-extraction channels are produced through the coffee puck.
Important factors to consider when tamping
- Never hit the filter holder once the tamper has created the coffee puck. If this happens, cracks may appear in the coffee puck, and channeling may occur.
- Never add coffee to a wet or damp basket, as this will cause the coffee to become damp, and the tamping will not work properly.
- Tamping can only be done once; it does not matter how much you press the coffee. One single movement is enough.
- If the puck is uneven, do not try to add pressure on the opposite side, as you will create internal channels and obtain equally bad results. You can take this puck out, break it well, and try to compact it again.
