Coffee Data Science
IMS Big Bang Espresso Filter Basket: An Analysis
Trying something new
A few months ago, I reached out to IMS to see if they could make me a prototype shower screen based on my experience with reducing the shower screen opening. They kindly obliged me, and they also sent me something special. They sent me a few sizes of their unreleased Big Bang Filter basket.
They asked for technical feedback, and I ran some tests.
Side-note: IMS didn’t ask me to promote their new filter basket or post about it. I have been doing technical comparisons of baskets over the years, so I was naturally interested in doing the same for this basket because of its unique design.
The Big Bang
The hole layout of the basket is unique because the hole spacing gets smaller as you get closer to the center. The aim was to allow higher flow through the center to offset side channeling.
The filter basket does not have holes all the way to the edge like many of the newer filter baskets, and it is made of aluminum compared to the heavier steel baskets like the Wafo and Unifilter.
Equipment/Technique
Espresso Machine: Decent Espresso Machine and the Kim Express
Coffee: coffee from Chromatic and Sweet Maria’s Home Roasted Coffee, medium (First Crack + 1 Minute)
Shot Preparation: Staccato Tamped
Profile: Ramping Bloom
Filter Basket: Wafo Spirit and IMS Big Bang
Other Equipment: Acaia Pyxis Scale, DiFluid R2 TDS Meter
Metrics of Performance
I used two sets of metrics for evaluating the differences between techniques: Final Score and Coffee Extraction.
Final score is the average of a scorecard of 7 metrics (Sharp, Rich, Syrup, Sweet, Sour, Bitter, and Aftertaste). These scores were subjective, of course, but they were calibrated to my tastes and helped me improve my shots. There is some variation in the scores. My aim was to be consistent for each metric, but some times the granularity was difficult.
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).
Intensity Radius (IR) is defined as the radius from the origin on a control chart for TDS vs EY, so IR = sqrt( TDS² + EY²). This metric helps normalize shot performance across output yield or brew ratio.
Data
I pulled 12 pairs of shots with identical parameters. I pulled quite a few other shots, but I was trying to balance a few other experiments. In terms of taste, they had similar performance.
However, if I split taste by machine, the Kim Express had an improvement in taste.
This is related to TDS and EY. Overall, the picture seemed mixed.
When separating the espresso machines, the Big Bang pulled more similar to the Wafo Spirit. However, this was not true for the Decent.
The individual scores showed the Big Bang not to perform as well, but from a statistical level, these differences were not significant.
Summarizing these experiments, the differences between the two baskets across all variables were not statistically significant.
General Population of Shots
While I didn’t have too many paired shots, I do have a good population of shots. We can view this data as a control chart of TDS vs EY. This chart contains 90 shots on the Decent Espresso and 35 on the Kim Express.
We can break this down by machine. On the Decent, there are not as many shots. I did not find it to perform as well for my current Decent profile.
For the Kim Espress, the two baskets perform in line with each other.
This data leads me to believe something in the Decent grouphead is still not behaving optimally. Obviously, I have gotten it to perform well for the Wafo Spirit, but does the difference in performance indicative of some unknown water flow phenomena? This is a fair question considering how I have matched shower screens for both machines.
After these initial tests, I decided to use the Big Bang exclusively for my Kim Express. Also, I didn’t want to bring a basket back and forth from work. The Big Bang has worked great for my lever. I’m very curious how lever and pump machine could differ so much when I have tried so hard to bridge the gap between those machines.
If you’re looking for a new basket at a lower price point, I suggest looking at the Big Bang.
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