A Finer Look at the DISK FINE


Weeks back, Prima Coffee and Able Brewing  came up with a clever proposition – of which I am so grateful a beneficiary: manufacture and distribute 100 prototypes for a new metal Aeropress filter and select 100 applicants to share their thoughts.

This iteration of the DISK is Able’s third in a relatively short time period and shows a commitment to innovation, R&D, and quality that many companies in the industry should regard as a shining example.  Each version has seen a reduction in the hole size to eliminate fines (dust size particles – a byproduct of grinding coffee) from finding their way into the cup.

The purpose of this post will be to summarize how effectively I found the DISK FINE accomplishes this goal, as well as an evaluation of the overall cup quality I was able to achieve with its use.

THE PROCESS

Two home grinders and two shop grinders (Baratza Preciso, Baratza Vario; Mahlkonig Guatemala Lab, Ditting 804) were used to test the filtration of the DISK FINE across different grind profiles.  Each brew was executed using the same brew recipe and to the same level of extraction.¹  After tasting, a sample was filtered then measured through the VST Lab II refractometer to ensure extraction consistency.

The extraction can be seen plotted on the Universal Brewing Control Chart below.

THE RECIPE

I’ve Aeropressed myriad ways in an attempt to achieve the most consistent and even extraction.  While there are many ways to get a great brew, here’s the recipe I’m currently on and used for this analysis:

Dose: 15.5g;    Brew Water Weight:  240g;    Total Brew Time:   2 min 30s

TDS%: 1.4       Extraction:  19%

Inverted, the Aeropress is preheated.  The water is discarded and 15.5g  of finely ground coffee is dosed into the Aeropress.  240 g of water at 205F is poured over the coffee in concentric circles for 00:15-00:30 (seconds).

At 1:00, the bloom is pat down and the brew is given 5 stirs – enough to lift the settled coffee from the bottom of the chamber.  Immediately, the Aeropress is inverted (right side up) while rotating 1x around to ensure no grinds stick to the plunger or upper walls of the chamber.

At 2:00, most suspended grounds have settled into a puck at the bottom of the chamber.  The plunger is taken off to let gravity do its work, then placed back on and pressed slowly for approx.  30s until the air gap above the coffee hits the puck (cue hissing sound).

While NOT inverting can make sense with a paper filter, doing so drastically increases the fines through the metal filter since the velocity and turbulence of the water pushes the fines through the filter holes.  When inverting, the fines settle on top of the puck, and so with a gentle plunge, remain there instead of migrating into the cup.

THE RESULTS

The first thing I noticed with the DISK FINE was how much less resistance (more flow) it had compared to the  previous generation.   However, while I assumed the extra pressure would result in having to go finer, the extraction levels between the two filters were constantly very similar for a given grind setting.

You can see a comparison of the hole sizes/quantity/distribution below between all three generations of the filter. While the DISK FINE’s holes (far left) are much smaller than its predecessor, there are also many more of them – so much so that it offers significantly less resistance.

3rd Gen DISK (FINE)

2nd Gen DISK (008)

1st Gen DISK (01)

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Overall, I was able to achieve some very nice cups of coffee through the DISK FINE, and can say that the best cups from that filter were preferable to the best from the previous generation (008).  There were palpably less fines and overall the cup just came off as being less muddled with cleaner, more articulate flavour.

These, however, were the best cups and some others told a bit of a different story…

The success of achieving a cleaner cup largely seemed to depend on two factors:  the quality of grind and the fineness of grind.   Among the grinders used, those which created more dust-like fines (really fine fines) resulted in more fines in the cup under certain conditions.  This is in complete congruence with the filters hole distribution and design: while the holes are small, dust-like fines are certainly still smaller and will make their way through; since there are many more holes in the DISK FINE, it has a larger total open sq area than its previous generation counterpart and so will allow a larger amount of very fine fines to come through.

2nd Gen DISK Fines (lower quality grind)

3rd Gen DISK fines (lower quality grind)

-The sample to the far left is the previous DISK (008) with a lower quality grind.  You can see that while the fines in the cup are larger, there aren’t too many of them.   

The sample to the immediate left is through the DISK FINE with a lower quality grind – note many more fines present.  

The other variable which seemed to affect the amount of fines in the cup was the grind size.    As we found with Coava’s KONE filter, grinding finer (accompanied with the right pouring technique) counterintuitively resulted in less fines.  It seems less obvious why this would be the case with the DISK v. the KONE, though we can theorize that under low pressure, a finer grind “locks” the fines into place resulting in less fines-migration to begin with.

THE VERDICT

Overall, I am quite pleased with the DISK FINE.  On the positive side, it is an exquisite piece of manufacturing and with a decent quality grind, results in a very clean cup.  Further, even cups that weren’t the tastiest were still quite good and merely accompanied with a slight off aftertaste.

However, there is no product that is perfect in every application and there were a few areas that the DISK FINE fell a bit short:  while the home grinders used in these experiments were of high quality, most home grinders will result in a less homogenous grind and so more fines.  Whether the very fine fines that make their way through the 3rd Gen Able filter are of actual concern for home coffee brewers using a lower quality grind will become evident with more use.

The only other negative point is the reduced thickness of the disk (necessitated by being able to accurately manufacture smaller and more holes).  While the disk itself is a beautiful piece of work, the tradeoff is a less sturdy, more flimsy product, the longevity of which is to be seen.

Ultimately, these are just a few findings through a narrow set of experiments.  Others will almost certainly have experiences with this filter that are inconsistent with those stated here and an accurate impression will only come with time.

Until then, I’ll try my best to keep playing and see what comes out of it.

¹note that while different extractions were attempted and evaluated, I found the brew recipe stated to taste best and utilized it as the constant through most variable test conditions.

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