How to make better espresso with a precision portafilter strainer

What does an espresso basket mean

To begin with, a short introduction for the self-preparing espresso lover. The espressobasket (bowl, strainer, filter) is a metal removable part of the machine. Specifically, it is inserted into the portafilter, i.e. the lever of the coffee machine. It serves to hold the ground coffee and is the place where theextraction of the coffeetakes place.

It is the basket that carries the ground and compacted coffee to the head of the machine. It looks like a small stainless steel bowl but has holes in the bottom. That's probably why the name strainer fits better. If it doesn't have a hole in the bottom, it is a blind strainer - a bowl used to backwash the head of the machine when cleaning it.

IMS vs. VST and other portafilter strainers

The portafilter into which the basket is inserted determines the correct basket size. Therefore , thediameter, depth and shaping of the bowlmust match the

the lever of the coffee machine. Of course, you can get a portafilter strainer with the ideal dimensions when you buy a lever coffee machine. Direct from the manufacturer, their branded baskets will come packaged with levers and accessories for your coffee maker.

So now you're thinking, "what's the big deal, I got the baskets from the manufacturer, why bother with this anymore?". Well you are exactly my target readership. The basket problem is exactly you if:

  • it's beenmore than a year since you've had a coffee maker and you've never properly checked your coffee maker's strainers, let alone changed them
  • you want excellent espresso and something betterfor your machine than aprefabricated portafilter strainer
  • you want to make single espresso properly (only make single espresso lever coffee with precision straight-walled baskets)
  • you suffer fromextraction problems such as coffee particles in the cup, wrapping and channelling, unbalanced coffee taste

Precision espresso filters from IMS and VST

First things first - you can of course make good espresso with traditional portafilter cups from the coffee machine manufacturer. But... do you want to get all the "flies" out of your espresso and have really great coffee? Get cups fromIMS or VST: manufacturers of precision portafilterstrainers.

Why are VST and IMS precision strainers?

  • They have precise filter perforations

What I mean by this is that the way they make their cups is thought out to "micro detail". For one thing, there's the actual use of top quality stainless steel and the optimized placement and density of the holes in the bottom of the strainer. Secondly, the precision of each hole's specific size (micro size) and rim structure - the shape and smoothness of the holes forming the espresso filter.

Differences between espresso filters

Choosing a replacement portafilter basket should meet you afterabout a year of use in a coffee shop and two years for a home espresso machine (replacement time is relative, depending on how it is handled and the amount of use over the year). On its own, the metal basket will last for years, but as wear increases , its functionality decreases - damage to the bottom perforations, manual "accidents" to the basket.

When you go to our espressoshop looking for a new espressobasket, you'll be guided by the dimensions:

  • portafilterdiameter,
  • thevolume ofthe coffee dose.

Dosage - the volume of the cup is related to your espresso recipe, i.e . theextraction ratio. Therefore, from a 14g bowl of ground coffee, I calculate that you will make 28g of espresso: ex: 1:2. The same recipe will work for an 18g bowl of portafilter = 36g of espresso. The diameter is determined by the size of the portafilter or the head of the machine. And then there is the specific processing of the strainer.

Does the correct strainer have straight sides or rounded curves?

Note that at first glance the visible difference between a VST strainer and a regular portafilter strainer (both for the same coffee weight) is in their shape. Straight walls vs. curves. In both, espresso extraction occurs, but it happens a little differently in each.

Through the coffee in the VST strainer, the water is allowed to flow evenly, almost perpendicular to the cup. On the other hand, the greater the slope of thecup's curvature there is an increased amount/flow of water at specific points. Which is dangerous in terms of extraction uniformity and thedevelopment of channelling problems.

Perforation of the espresso filter

What you can't so easily discern with the eye is the size, shape, location and density of the portafilter strainer holes. What can happen when an espresso filter doesn't have precise perforations:

  • Incorrect hole shape and size = coffee particles clogging the holes or alot of particles getting into the cup,
  • uneven distribution or few holes = uneven extraction of coffee.

Advantages of VST strainers in practice

Baristas in Portland conducted an experiment with 40 cups of espresso prepared alternately using a classic and a VST cup (20x VST and 20x classic cup). By recording how the extraction yields (final espressos) differed they then obtained data to compare the error rate - the inconsistency of extraction when using the VST or classic cup.

Infographic of the variation in espresso extraction with a VST precision basket and a regular portafilter strainer. According to:

Another factor investigated in this experiment was the problem of channeling. TheVST portafilter basket came out victorious, both in terms ofeven espresso yield and in the channelling test. For each espresso, it was noted whether there was a major, just some, or no channelling problem during extraction.

Does the use of a VST and IMS filter make a difference to the taste of the espresso?

The English baristas at Perfect Daily Grind were interested in the user perspective in the differences in filters. If there are differences in taste and which coffee tastes better. This time, only in a contest of precision strainers. What do you think, did the espresso taste better in the IMS or VST cup?

So they also took both types of strainers and tried their hand at making coffee. Again, the same coffee, grinder and extraction ratio. The significant difference was already in the preparation, where they needed to adjust the grinder by 1-1.5 degrees for a finer grind when using the IMS cup.

Thus, the change in grinding apparently resulted in a more consistent grind and distribution of coffee particles. Which also resulted in a smoother and sweeter note in the espresso flavor. However, there was hardly any difference and the differences were undetectable when milk was added. This advantage does not suit grinders that would struggle with the fine grind of an almost Turkish coffee.

Comparison of precision strainers to a portafilter. Which is better?

The portafilter basket from VST:

  • Portafilter cups used at the World Barista Championships
  • 100% of the holes of each VST filter are measured to within +/- 20 µm for min and max limits in surface area and pinhole diameter
  • circularity, location, throughput and area coverage are measured
  • holes are centred to +/- 1.0 mm
  • wide inlet angle against filter clogging
  • Patented design for long life and minimized wear effects

IMS portafilter basket:

  • Patented perforation technology guaranteeing circularity and conical perforation shape across sections
  • The surface inside each conical hole is polished to remove any irregularities
  • coffee oils can flow freely through the filter without any obstruction
  • hole diameter from 0.25mm to 0.40mm
  • 3 types of IMS perforations with different positioning and distances between the hole axes to adapt to the extraction and the user

Drawings of the three perforation variations of IMS precision espresso filters. Image source: IMS