Coffee Data Science

Espresso Shots Doing the Splits

Radial and Cartesian Cuts

3 min readAug 18, 2023

Espresso is complex and difficult to understand. The tools to help dissect the shot as the flow of water varies quite a bit. I have done some studies using a larger spaced grind, but these weren’t super easy to do. More recently, Wafo made a few prototype tools to explore extraction, and I had the opportunity to take a little bit of data. This data is only exploratory, but these types of tools would be very interesting if they were more common.

Equipment

These shots were pulled on the Decent Espresso machine before Thermal Pre-infusion, but I was still close with my Pump & Dump profile. I used the Acaia Pyxis scale, the Difluid R2 refractometer, and the Wafo Spirit basket.

These tests looked at TDS and EY. I didn’t make taste notes, but there was a clear taste difference between the splits.

Total Dissolved Solids (TDS) is measured using a refractometer, and this number combined with the output weight of the shot and the input weight of the coffee is used to determine the percentage of coffee extracted into the cup, called Extraction Yield (EY).

Cartesian Cuts

The shot splitter was nice, but cups are usually larger and circular. It would have benefitted me to have four tall cups. These are the cups and the shot splitter divide.

I was surprised to see the percentage of output coffee varied so much, as did what was contributing to extraction. Like the bottom quarter had the lowest output but not the lowest contribution to extraction yield.

Radial Splits

This tool was the one I was particularly interested because it is difficult to see the center of the filter during the shot even with a low flow profile.

The inside was wild. Based on the original images posted from Wafo, the circles aren’t quite evenly spaced, so I measured them in the image to help estimate the total percentage of the area covered by each circle.

The distances between each ring were close, but the area greatly enlarged due to more circle being available.

Surprisingly, the center of the filter had the most flow, but the flow to the outside was similar. The extraction was more even than I thought it would be, but I didn’t get a chance to use this tool to do tests without my grouphead modification or on my lever machine.

Given another chance, I could spend weeks doing experiments with these tools. These tools are much easier to use than my other tools, and part of the user experience is the ease at which one can use any tool.

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