Espresso Perfection Technique #1 - Tamping

by Don Holly

There is a definitive clue as to the level of skill and knowledge of the barista preparing an espresso beveragehow he or she tamps the coffee. Tamping is the compacting of the ground coffee in the portafilter prior to brewing. How a barista tamps will be a major determinant to the quality of the espresso, because compacting the coffee firmly and uniformly forces the water to flow through the grounds in a manner that extracts the best of the coffee's flavors.

Unfortunately, a proper tamping method is rarely performed by most baristas in the United States. At most, you will see a mild flattening motion where the server gently lifts the dosed basket up to a tamping plate mounted on the outside of many grinders. Some baristas have heard that firm tamping is important, but really don't understand the mechanics. In this case, you will see the barista pressing firmly on the coffee and than rapping the side of the portafilter violently and repeatedly, as if it were necessary to kill the coffee before brewing it.

Tamping is necessary because the brew water is under major pressure (8 to 10 times the weight of gravity) and will have an almost intelligent ability to find the path of least resistance through the coffee. If it does find channels that are easy to get through it will rush through these areas, overextracting the coffee surrounding the channels and underextracting the coffee in the channels. The resulting beverage is the worst of circumstanceswhat flavor does get into the cup is bitter and astringent, and so much of the coffees potential good flavors remain behind in the portafilter basket. With firm and even tamping, the water has no choice but to flow through all of the coffee uniformly, and if the barista has adjusted his or her grind correctly and the espresso machine is in good order, the resulting coffee beverage represents the best the coffee has to offer.

So how do you tamp correctly? Well, now that you know why you tamp, you can apply your intelligence and sense of feeling to the challenge. You can try this at home or politely inform a misinformed barista on these steps of proper tamping:

Step 1: Having dosed the proper amount of coffee into the portafilter basket, even it out so that it is level in its distribution in the basket. Any "high" points will result in areas more compacted than "low" points after tamping, so it is important that the coffee be packed full and level in the basket.

Step 2: Use a flat-faced hand tamper and a counter that is low enough so that you can lean into the tamper with your body weight and arm straight. The tamper should be held in your relaxed hand as an extension of the arm. The tamper face needs to always be applied straight into the coffee, without an angle, because any canting will result in an area where the coffee is thinner.

 Step 3: Note that the diameter of the tamper is slightly smaller than the inside diameter of the basket. If you just tamp in the middle, the outside perimeter will still be loose, exaggerating the tendency for the water to flow between the basket and the coffee. I recommend employing the "Staub Tamp" where you tamp the coffee four times riding the tamper up against the inside of the "North, South, East, and West" edge of the basket. Tamp with 30-40 pounds of pressure (in training we tamp on a bathroom scale on the counter). This evenly compacts all of the coffee giving the water a uniform bed to percolate through. Do not tap the portafilter handle between tamps, as this will just tend to loosen adhesion between the packed coffee and the basket. When releasing pressure from each of the four tamps, give a slight twist to the tamper to polish the surface of the compacted coffee.

Step 4: Inspect the result of your tamping to make sure that it was even and there is a good polish. If you notice that one side is deeper than another, you should really knock out the grounds and start over again. If everything looks acceptable, then mount the portafilter handle into the espresso machines group head and begin the brewing cycle.

Step 5: Your final step in tamping is quality control assessment. Noting the quality of the extraction (and of course the best duty of all is tasting the coffee!) is critical to improving your tamping skill. Also examine the spent coffee in the basket after brewinglooking for "worm holes" which is a sure sign of channeling where the water found a weak spot in the coffee pack. The knocked out grounds should have the form of a puck; if it's mush then the grind and the tamp were off. Don Holly

Ultimately, the quality of the espresso will be a reflection of the training and the consciousness of the barista. Nowhere is this more apparent that in the tamping technique of the barista.

Don Holly is administrative director of the Specialty Coffee Association of America in Long Beach, CA. He can be reached at 562.624.4100.


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