Tamping is the act of compressing the coffee grounds into a "puck" of coffee in the filter basket prior to extraction. You should learn to tamp to produce uniform results in a reproducible way. Since proper tamping is essential to making excellent espresso, we recommend that tamping be done by hand using a coffee tamper in accordance with the following procedure. Tamping by using the tamper that is integral to your commercial coffee grinder is not recommended.
Making the Perfect Coffee Puck
First, place the filter basket (portafilter) into the group handle, attach the group handle to the grouphead on your commercial espresso machine, and use the manual override switch to run some hot water through the portafilter to make sure that the mesh is clean. Then take the group handle, and put it into the loading bay on your commercial coffee grinder. Pull the dosing switch once for a single dose, and twice for a double dose.
For you homeowners and office-dwellers using home and office espresso machines, you can simply measure out a dose (¼ ounce for a single, and ½ ounce for a double) using a dosing scoop, and put the coffee grounds into your portafilter.
Shake the group handle back-and-forth rapidly, using a small range of motion. The goal is to distribute the coffee grounds evenly within the filter basket so that there are no "holes" through the puck (with metal showing) and no "pockets" within it. Shake the group handle so that the top surface of the coffee grounds is (approximately) level.
If it helps, you can tap the filter-basket end of the group handle against your other hand (or against anything else that is clean) to help to even out the coffee if you can't quite do it with simple shaking. If you are making this puck for yourself, you may also use your finger to help smooth out the surface of the coffee, but it is unprofessional to touch the coffee with your fingers if you are doing this in an espresso bar or a coffee shop.
Using the Coffee Tamper
You will then compress the coffee grounds with a handheld tamper. These tampers are either wooden, or stainless steel. Obviously, you should use a tamper that fits your portafilter. When purchasing a tamper, make sure that the tamper that you get will work with your commercial espresso machine. You should not clean your tamper in a dishwasher. Use a cloth, and soap with warm water.
You will use the tamper to compress the coffee grounds using 40-45 pounds of pressure. To learn what 40-45 pounds of pressure feels like, take a bathroom scale, and press on it with the tamper (put a clean paper towel down, or wash the tamper afterwards) to practice. After a little practice, you should be able to push with the right pressure fairly consistently.
Push the blunt end of the tamper (the working-face) into the filter basket. Push down with the pressure that you have practiced (40-45 pounds), and then give the tamper a quarter twist, and pull it out of the filter basket as you continue to twist your wrist. Continuing to twist as you remove the tamper will ensure that no coffee grounds cling to the tamper as it leaves the surface of the puck.
After this first tamp, there still may be a ridge of coffee grounds around the edges of the coffee puck, and there still might be some coffee grounds around the rim of the group handle. Turn the tamper around in your hand, and sharply tap the filter-end of the group handle with the handle-end of the tamper. This will dislodge the loose and misplaced coffee grounds, and knock them into the center of the surface of the coffee puck.
Never tap the group handle with the working face of the tamper. We do not want to put any dents or gouges into the face of the tamper, since we need it to produce a flat, uniform coffee puck.
Now will do a second, lighter tamping to press the newly dislodged coffee grounds into the puck. Put the blunt end of the tamper (the working-face) back into the tamper, and push down again, with about half the force that you used on the first tamping. The idea here is to integrate the recently dislodged coffee grounds into the puck; it is not to compress the puck more.
As before, twist your wrist as you remove the tamper so that coffee grounds to not adhere to the surface of the tamper as it leaves the surface of the coffee puck. You are almost done.
Protecting Your Commercial Espresso Machine
The second most common repair needed on most commercial espresso machines is that the gasket in the grouphead needs to be replaced. This gasket should form a watertight seal, and should maintain the pressure (from the pump in the espresso machine) within the grouphead during an extraction. This gasket is the seal between the group handle and the grouphead.
When this gasket starts to wear out, the pressure will not be maintained within the grouphead (which will result in under-extraction of the coffee puck, and weak espresso), and when the wear gets worse, water will actually leak out of the grouphead and around the group handle during the extraction.
While all gaskets will eventually wear out (or dry out if a machine is not used for a long period of time), this gasket is worn out very prematurely in many coffee shops because of the careless use by operators in omitting this final, and very simple step.
For commercial espresso machines used only in the summer (or winter) months in beach (ski) resort towns, we recommend that you remove this gasket and lubricate it with olive oil or Vaseline, and leave it in an airtight plastic bag during the off-season. This will prevent the gasket from drying out.
Coffee grounds are very hard - almost (but not quite) like grains of sand. Following the dosing and tamping steps outlined above, there still might be just a few coffee grounds still sitting on the rim of the group handle - even if you don't see them with a quick glance.
If you insert the group handle into the grouphead, and twist it to lock it in, these few coffee grounds will act just like sandpaper. They will scratch the gasket badly. Hundreds of such insertions over the course of a week will put an enormous amount of (completely avoidable) wear and tear on this gasket.
The Final, Simple, Finishing Touch
While holding the group handle in your dominant hand, brush the palm of your other hand across the filter-end of the group handle to remove any coffee grounds that may remain on the rim of the filter basket. This will save the gasket in the grouphead.
You can now insert the group handle into the grouphead, and give it a twist to lock it in. You're ready to go.
...written by your friends at
The Coffee Brewers