I often get calls from people having difficulties with their espresso recipes or taste descriptions. “The coffee seems to taste different than when I brew it in my shop, how come?” Obviously there are a million variables that affect this flavour composition. However, one of the first things I check when I inspect an espresso machine is the portafilter basket.

The theory

There are different basket sizes used for different dosing quantities. VST, one of the most prominent basket manufacturers, named theirs by recommended weight, though it depends on the roast level, bean density and pre-infusion. These sized are 15 grams, 18 grams, 20 grams (competition basket) and 22 grams. Generally, people use the 17 grams baskets for generic recipes or the competition baskets to train with. Larger baskets have a larger hole area to allow for similar shot times. Since VST baskets are laser-perforated and extensively checked, their deviation is quite small (+- 4%) compared to other baskets (+-15%). The chart below shows a comparison between regular La Marzocco baskets and VST baskets.

Model Base diameter Hole.avg Hole.area Shape 1 430 401.9 50.7 81.9 S 2 430 409.9 46.3 85.0 S
Vst. 15 494 310.6 14.3 54.3 H
Vst. 18 494 351.2 9.8 69.3 H
Vst. 22 494 377.1 15.4 80.0 H

IMS, the other main brand of baskets, simply used the height as the size indication. Their sizes are 24mm, 26mm and 28mm. This range is offered in two shapes of the basket sides: straight or curved.

The study

Even though numerous studies have already been done comparing these basket types, I wanted to experience these differences for myself. I prefer to take a taste-based approach rather than measuring. I brewed espressos with all filter baskets available and compared dosing potential, shot times, extraction balance and mouthfeel.

The results

The three IMS basket sizes seemed to correspond to the VST basket sizes, though IMS could contain a tiny bit more coffee. The perforation area of IMS baskets seemed a bit larger since shot times dropped from 28 seconds to 24 seconds when switching from a VST basket to the corresponding IMS basket. This means I could grind finer with the IMS baskets for the same shot time. However, flavour-wise VST baskets seemed to produce higher extractions.

Furthermore, IMS baskets seemed to produce more clarity and sweetness in the coffee. VST, on the other hand, gave more body but also made the acidity a bit harsher. Upon cleaning the portafilter after brewing a shot, I found the IMS baskets to contain more oils than the VST baskets. This might be the reason for this difference in mouthfeel, since those oils would give an espresso more body and more bitters.

Finally, I do not recommend the curved IMS baskets. For every size, these baskets seemed to produce a bit of channeling and therefore an imbalanced espresso.

Conclusively, I think IMS filter baskets are definitely something to consider; preferably H26 since it allows for 19 – 20 grams dosing which is a generic espresso dose. It simply made coffee more articulate and bright, which is something I’m always aiming for when brewing espressos. A customer of mine did not recognize the coffee (pulped natural Brazilian yellow Bourbon) she used in her shop when I brewed it with a VST basket. However, when I switched to the H26 IMS basket that she uses, it was pretty much the same beverage she serves. Of course VST baskets have proven themselves to give high, consistent extractions and should also be considered. It depends on whether you aim for the highest possible extraction, or for something more related to a home barista’s setup, or if you just go by flavour. There’s no best, but there are certainly huge differences.

Have you ever compared these baskets? Or are you interested in learning more about the differences or this experimental setup? Feel free to leave a comment below.