A couple posts ago, I made a list of Must Have Breville Accessories. My third suggestion on that list was to get yourself a precision filter basket, and a saw that a LOT of you were very interested in this. So, I thought I’d make a dedicated post explaining what exactly makes these baskets better than stock ones, and what kind of results you can expect from getting one.
With espresso, you want to try to extract the puck as evenly as possible. Things such as removing clumps, tamping out air pockets, and ensuring a level surface are easy ways to help achieve this. However, one often overlooked aspect is the filter basket itself, and that’s because it’s not something that’s visible to the naked eye.
Can you see the difference between the holes in these two baskets???
How about NOW? I put the stock Breville basket and the IMS under a microscope. On the left is the stock Breville, and on the right is the precision IMS.
Although these may seem like very small imperfections, they represent a large percent change in overall hole area. John Buckman from Decent espresso actually did a great summary of this by explaining that at brewing pressure, a 0.2mm hole let’s through about 0.8mL of liquid per second, whereas a 0.3mm hole let’s through 1.6mL per second. So if your basket contains a patch of over or undersized holes, or under or overly SPACED holes, it will skew the flow towards or away from that part of the puck.
To validate what I was seeing under the microscope, I spent the afternoon pulling bottomless shots on both the stock Breville filter basket and the IMS, recording the extraction time, extraction percentage, as well as if I saw any noticeable channeling. And here were the results.
The IMS basket had a significantly faster flow rate at the same dose and grind setting, so, I was able to grind two whole steps finer on the Barista Pro to slow it back down. This contributed to extractions that were about 0.3% higher on average compared to the stock basket.
In terms of visible channeling, things were about equal. Each basket had one or two shots with squirting but there was no real observable advantage to either.
However, numbers only tell part of the story here. When tasting, I found the shots from the IMS basket to have significantly better clarity, and less overall bitterness compared to the stock basket. It’s not a mind-blowing difference, but it absolutely is present.
So, all of these things combine to explain why I included these as one of my most recommended accessories for Breville machines. I would be interested if some other big manufacturers also jumped in and started making 54mm precision baskets, but for now, IMS appears to be the only ones. So kudos to them!