While I love learning about the minutia of all that is coffee (different steeping methods, pre-infusion, pressure profiling, ideal roast dates, roast curves, etc…) I have found it refreshing to ponder the baby steps that every barista takes when they first enter the coffee world.
Please do not consider this post to be by any means authoritative, simply a re-statement of the building blocks upon which the finer points are built. It is intended primarily for the new wave of up-and-coming coffee professionals and enthusiasts, but may spur the more experienced to do a bit of experimenting as well.
I think a lot of baristas over-evaluate the influence of the tamp. I’ve often heard remarks like “that shot is dripping, I guess I tamped to hard”, or conversely “maybe I didn’t tamp hard enough that time”. Please throw this seemingly logical convention out the door. Extraction rate is determined by dose and grind primarily, the tamp has little to do with the actual extraction speed; it is primarily an influencer of how even an extraction is. Think about it. The coarseness of espresso grinds limits the coffee’s ability to be packed. In other words, there is a natural threshold at which the espresso can be packed no more. In order to actually tamp it further, one would have to literally be grinding the coffee finer with the tamper. The espresso that you’re using has already been ground extremely fine, under intense pressure from heavy duty burrs that could take your pinky finger off. Do you really think that your smooth, flat, Reg Barber is going to do much damage? Didn’t think so.
Conclusion: Stop killing yourself with your tamp! A couple of years ago I developed an intense knot between my shoulders. Sound familiar to anyone? It was from repeated strain on my muscles cause by overexertion. I was tamping far too hard. At least 60 pounds, I imagine. Perhaps more. I always “knew” I only needed 30 pounds. That’s what I was taught. That’s what I’m sure most baristas have heard. But I think that many don’t realize how light that actually is.
On that note, how light is too light? I am reminded of an infamous experiment that many like to forget about. Dose a shot and pull it. No tamp. Loose coffee, straight into the group. It should gush out, right? Wrong. If the grind and dose have been set correctly, the shot looks remarkably decent…*tear. All this hard work and labour for nothing. Why tamp at all, then? First off, putting loose coffee into a group head will make one hell of a mess really fast. Secondly, there is very little control over how even the extraction is. Something is coming to mind….oh ya, “Extraction rate is determined by dose and grind primarily, the tamp has little to do with the actual extraction speed; it is primarily an influencer of how even an extraction is.” I knew I said that already.
Look at the videos from the WBC of the last two years. Watch how light they tamp. Finger strength. Beautiful. This brings me to my final point. There is far less control over how even the tamp is when you’re trying to pound the portafilter into the counter. Ease up, and may I suggest using your fingers to feel how even your tamp is? Every time! Too many baristas learn the basics, learn how to steam rich creamy microfoam and pour 8 leaf tulips, and then they begin to ignore these “minor” points. I’ve seen veterans, whom I respect a great deal, tamp very unevenly. Don’t get sloppy. Check every time. Try seeing how light you can tamp while still obtaining a good extraction. I’m curious to hear about what you find.