Coffee Data Science
To Better Understand Effective Top Paper Filters for Espresso
Experiments for deeper learning
Previously, I found an issue with the water dispenser in the Decent Espresso machine. It sits on top of the water diffuser which is on top of the shower screen. I have been using a star cut paper filter on top of the puck, but I wanted to see if I could better understand how to get more optimal performance.
I used spent to run through a few iterations of my profile and see where the water was going. This would give some clues because fresh coffee behaves differently. However, I didn’t want to waste a bunch of coffee, so I went with spent coffee first.
I did a long steam pre-infusion, and the center gets saturated last.
So I stopped the shot sooner, and the water really goes to the edge faster than the center. In this case, the water at the edge was almost at the bottom of the puck
I tried adding tin foil to see if I could block flow from the left side because the left side channels from the water dispenser.
This made the flow more even, as water was slowed down the sides of the basket.
I then opened the shower screen, and found I needed to replace the paper filter inside the shower screen. I had been experimenting with using a paper filter inside the shower screen to redistribute water.
I thought I could modify the water diffuser to block outer holes and see what happens.
The flow seemed a little more even, but something in the subsequent shot didn’t look right.
So I extended tinfoil just on left and right sides as those were causing more side channeling. This improved flow a little, and the next shot looked a little better.
The challenge with this modification is that it was difficult to separate it’s effect from other variables at play. I was hopeful to see a much bigger change, but so much of the water is mixed at the shower screen level that this change may not be optimal.
The end result of this investigation was that even though the star paper filter was helping improve shot performance, more could be done to make the water more evenly flow through the puck. My best effort still resulted in side channeling, so I continue looking for a better solution.
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