Coffee Data Science
Examining Single Filter Baskets for Espresso
Improving flow issues with a top metal filter
I have different history with single baskets than others. When I really got into using a lever machine, a double was too much coffee for me. So I got a single VST basket (7g), and I started using it extensively. For the past year, I went to an 18g basket, and I decided to revisit the single basket as the top metal screens have become more common.
My Former Single Life
When I first started using the basket, I wasn’t getting the syrupy shot I desired. I identified two reasons:
- Too much headspace
- Difficulty in getting the right output ratio
I solved both of these issues by putting 14g into a 7g basket. This is highly unconventional, but the design of single baskets hasn’t been greatly paid attention to. The massive amount of headspace typically ruined the coffee bed, and filling the space to the top seemed to reduce that issue.
VST Single Basket
Let’s take a look at a regular 7g shot using a metal mesh on top to reduce headspace and make flow more even.
As for the shot, it was slightly off center which is probably a reflection of my lack of practice for the past year on distributing a single basket.
After the shot, the puck looked pretty well together, which is a good indication that the shot was low on channeling.
Single in a Double Basket
I thought one benefit of the metal mesh is to turn a double basket into a single because the metal mesh would slow the water down so as not to disturb the coffee bed. I used 10g or half of what I would typically put in the basket.
The result was a decent shot. The most difficult part of the process was ending the shot for a 1.5:1 output to input which is 15g. Obviously, you could run a little longer if putting a single into a milk drink.
In looking at the puck, the coffee bed was pretty solid. There was channeling, but overall, it functioned very well.
IMS “The Single”
“The Single” was supposed to be designed to give a truly single shot. However, I found the side channeling to be overwhelming. I was very excited when I first bought it, but I abandoned it quickly as it was also hard to tamp without an auto-leveling tamping.
However, I gave it a go with the metal mesh screen. Also, I had an auto-leveling tamper, so it came out better.
There was still some side-channeling, and the puck doesn’t come out clean. It was alright for taste too.
Some Data Analysis
I have Extraction Yield (EY), Total Dissolved Solids), and Taste (Final Score in other articles). This should be taken with a grain of salt because I’ve pulled 100’s of shots with the VST Single basket, so it’s no surprise it does the best. The Pesado Double is using 10g of coffee with the metal mesh on top.
I love single shots, but I’ve invested quite a bit of time to improving shots in the range of 18 to 20g. I really enjoyed giving these baskets another round, and I like how the metal mesh can help with single shots. I haven’t done a comparison with and without the metal mesh, and maybe I should.
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