Espresslo – Slow Motion Espresso

Slow motion espresso – espresslo?

An espresso extraction from my Bezzera BZ99s espresso machine with a modified DIY bottomless / naked portafilter, filmed at 120 FPS in 720p. The dose was was 21g, and the coffee was a blend about a week post roast.

A Diagnostic Aid

Filming in slow motion with the naked portafilter is a great way to see how the flow progressed through the puck.

Initial stages

The espresso first appears around the perimeter of the basket, implying that the flowrate was greater here. This could be because I use a convex tamper, which might result in a more dense region in the centre of the puck, or could be related to edge effects and the shape of the basket (i.e. the slight radius results in higher velocities at the perimeter toward the bottom of the basket.

As the shot progresses

The region of the basket to the back left of centre remained “dry” for some time after espresso had appeared elsewhere. This again suggests a region where the coffee is more densely packed, or perhaps that the tamp was slightly off level.
Flow in this region also appeared in “patches” (this is particularly noticeable if you slow it down to 0.25 x speed), which might suggest variations in density (perhaps due to clumping prior to tamping).
The flow progressed to two wandering streams, before finally coming together as a slightly off-centre single stream. Towards the end of the shot, slowing down to 0.25 x speed reveals localised regions where the espresso was much lighter in colour. Some channelling was evident at the very end of the shot.

End result

Overall, the pour started out a little “drippy” for my liking, and wasn’t quite as tasty as the shot I had earlier this morning (which had a sightly coarser grind and faster pour).

Somehow, I don’t think this will be my last slow motion espresso!

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