Tamping is a fundamental step in the espresso making process and this often misunderstood function can dictate the success or failure of any espresso shot. Achieving the appropriate ‘weight’ behind your tamp is important for consistency, although the angle at which you tamp is also surprisingly influential. To grasp this, we look at the desired outcome of tamping – to compress the air out of the grounds before extraction and to create a level surface for the water to evenly pass through the coffee.
Any weak areas in the coffee bed will allow water to travel through the path of least resistance, creating a channel.
To identify if channeling has occurred with your shot you may notice:
- Shot bows inward and looks streaky in colour as it extracts.
- The body of the shot may look thin, watery and lighter in colour.
- The shot may have a metallic or astringent taste.
These occur because the coffee oils have not been adequately and / or or evenly dissolved. Channeling can arise from a multitude of sins:
- Not drying out the basket properly before dosing
- Uneven distribution of the grinds before tamping
- Weak tamping
- By tapping the loose grinds that are stuck to the sides of the basket knocking the puck of coffee loose.
Finally, posture and the angle at which you tamp can affect the possibility of channeling. Hold the tamper as if you would a torch, with the thumb pointing down. Stand side on to the bench and hold your elbow and wrist above the group handle at a 90-degree angle. Good posture during tamping will protect your wrists and joints!
So now you may see there is a lot more to this business of tamping than meets the eye. Try adjusting any bad behavior one step at a time and once you have mastered each element (sorry to sound like a broken record) keep this consistent in order to fine-tune your tamping stage of the coffee making discipline.
- Tamp at hip height
- Don’t stand too close to your bench
- You want to create a 90-degree angle with your elbow directly above your tamper.
- Hold your tamper as you would a torch with thumb pointed downward
- Rest tamper on top of tamped coffee and raise to eye level to check any areas of unevenness.