Even with world-class espresso beans and the best equipment in the world, an espresso can taste watery and sour if mistakes are made when squeezing ground coffee. Even the smallest mistake in tampering has a surprisingly large impact on flavor and can mean the difference between a delicious cup of espresso and an espresso that takes a long time to prepare but ends up in the sink. Therefore, the way the tamper is pressed into the coffee powder is decisive for the quality in the cup. We'll explain to you what to watch out for when tampering properly.
A tamper is a small pestle with a smooth or convex (slightly outward curved) metal surface. The diameter of the tamper should match the diameter of the screen insert. So if your screen is 58mm in diameter you should use a 58mm diameter tamper. Tamper is also known as coffee stamp or coffee press.
Tamping describes the compression of ground coffee in a sieve into a firm, uniform "coffee cake" with a smooth and flat surface. This counter-pressure surface on the ground coffee must provide sufficient resistance to water flowing out of the espresso machine at high pressure (approximately 9 bar). The tampered and hard ground coffee surface is therefore responsible for creating the desired pressure during espresso extraction.
Two-piece stainless steel tamper with wooden handle
Base diameter: 58 mm
The purpose of compression is to compress the ground espresso in the sieve straight and at the same height so that the water can move evenly through the espresso. This is particularly important to avoid so-called "channelling". "Channelling" describes the phenomenon that water always seeks the path of least resistance.
If the ground coffee is unevenly distributed, the water first passes through several channels. As a result, more channels are added, but overall the extraction is uncontrolled, intermittent, and erratic. If you tamper with the curve, the water will flow through the thinner part of the coffee disc and prevent the entire ground coffee from being drawn evenly. The result: Espresso will lack flavor (sour and watery), have a small body and a flat aroma profile.
You can also recognize the water channels formed by grooving after the cover on the coffee disc as cracks. This gives you clear proof that everything is not going right. Therefore, we recommend that you practice correct tampering. It is useful to screw a screw into a wooden board with a screwdriver. This trains the correct hand position of the tamper.
Find out below how to proceed step-by-step with proper tampering.
step 1
Place the portafilter filled with flattened ground coffee horizontally on a tamper mat or place the portafilter in a tamping station.
step 2
Place the tamper vertically on the portafilter. Due to its own weight, the ram lays flat on the ground material. Check the vertical position.
step 3
When you want to tighten something from above, hold the tamper like a screwdriver. The hand and forearm form a straight line. Now create a vertical contact pressure of 15-20 kg on the ground coffee. It does not matter whether you create exactly 15-20 kg of contact pressure. It is especially important that the ground coffee surface is smooth and solid. And you can do this if you strongly press the ground coffee with tamper.
step 4
Slightly reduce the contact pressure and turn the tamper about 120°. This will "shine" the surface of the ground coffee and remove any roughness. The end result should be a solid, smooth and flat coffee surface.
step 5
Finally, you should use your finger to clean the edge of the portafilter from ground coffee so that ground coffee residue does not scratch and damage the seals in the group head.
Tip: Do not knock the sieve edge after tampering.
After compaction, dust residues may have accumulated on the inner edge of the sieve. The inexperienced barista will tap the side of the strainer with tampering to send the residue from the side of the strainer to the center. We cannot and cannot recommend this process because it will cause the compressed coffee cake to separate from the sieve wall and sometimes cracks can occur. During espresso extraction, water will first gush through these cracks. This prevents the ground coffee from being drawn evenly. The result is a low-lying espresso.
Correct compression is essential for the espresso extraction to proceed perfectly. Only with a tightly compressed "#coffee cake" with a smooth and flat surface can a counter pressure surface be created that provides sufficient resistance to water. First of all, make sure to compact it flat so that the surface of the ground coffee is absolutely flat. Only then can all the ground coffee be ground evenly. In this way, all valuable aromatic substances are released from the coffee.
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