Tapping the portafilter creates channeling
Dennis, our frequently opinionated Espresso Wizard, expressed concern to me today that our baristas are tapping the side of the portafilter with the tamper after they tamp and before they polish. This did not come as a surprise to me; I also tap the side of the portafilter after the tamp and before the polish. Dennis says that this is a "No No" because the tapping action ruins the carefully and uniformly tamped coffee matrix that you have just created, and makes channeling (uneven extraction) very likely. I understand why he says this, but I don't agree quite yet. I have to check it out for myself, which means pulling two shots with the same grind, dose and tamp, one without the tap and one with the tap.
Any thoughts, baristas?
posted by Sarah Wilson Belzile @ 5:01 PM
3 Comments:
LOL;
I've only been preaching this since, oh, 2002 or thereabouts ;)
It all started for me when a bunch of circumstances and discussions added up to some thinking...
In the space of two weeks, I found out about the inner workings of the Swift grinder (while it was still being developed); heard about Staub's tamp style, and read the Illy Chemistry of Quality book and read in depth about water "finding the path of least resistance"
Out of this, I got hrm - bottom of the puck is barely compacted when you hand tamp (discoveries when developing the constant-tamping Swift); how Carl Staub's method worked at creating a better seal on the sides and edges of the filter basket; and really, for the first time thinking deeply about something I'd rarely heard of before - channeling and pitting.
So I stopped knocking the side of the PF. Started with the staub tamp, then moved to a modified version. And I noticed that my channeling issues went poof.
Shalom Sarah,
I'm pro-tap. I think of it as allowing all the little grains to find their natural space in the matrix.
B'shalom,
Jeff
Well, after Dennis informed me this information about channeling while I was making his usual Devils brew, I stopped tapping the side.
This was much messier; so I tried both ways and timed it. There wasn't a difference in time or taste.
Since then I have been trying to quit the habit of tapping-mostly because it makes sense to me that tapping the side would disturb the already tamped espresso. But I do miss the cleaner, tapped tamp.
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