From budget to boutique, a grind uniformity love story.

25.05.19

From budget to boutique, a grind uniformity love story.

Now they say a bad workman blames his tools, and in the world of coffee I’ve always thought the equipment should be blamed before the product itself. An espresso that keeps channelling during service, a batch brew tasting a bit thin. Before blaming the coffee you should always check your procedures and equipment. Are you distributing that dose evenly ? have you tamped level ? has the grinder been cleaned and aligned? If you can answer yes to all of these questions then we can start analysing the coffee in question.

The main tool in a barista/homebrewers arsenal is their grinder.  These come in all shapes and sizes, from budget hand grinders, to high end boutique single dose machines that can adjust the grind size down the microns (take a bow Lynn Webber) ! At Crankhouse we sell grinders, across the entire range to coffee shops and the home brewer. One of the latest grinders to join our roster is the Wilfa Svart grinder,  an entry level filter grinder developed in Norway with the help of Tim Wendleboe (if you don’t know who this guy is give him a google, he's a bit of a coffee superstar). This grinder has taken up a space on many a kitchen counter around the world and for good reason, it's received great reviews and I personally know a few people with them that love and get great results.

However, a few weeks ago we happened to receive an email from the Wilfa UK distributor saying that they'd had a new unit returned from one of our customers due to “uneven grind consistency, and not suitable for filter!” The customer was sent a replacement directly by them and subsequently the second unit was returned with the same complaint. After reading the email, in slight disbelief my first remark to Dave was “what was he expecting an EK for £100 ? !".

They even posted a review on our store for the Wilfa:

"NO GOOD FOR FILTER COFFEE

At the coarsest setting the coffee was far too fine for a V60. The UK distributor Brewed by Hand, sent me a new one immediately and when this proved to be grinding in the same way they organised collection and a refund. Great service from the distributor company but extremely disappointing grinder." 

In the world of coffee grinders (like everything else), the general rule applies: the higher the price the better the components. These allow for a more even grind size, mainly the burrs.. a set of Mahlkonig EK43 replacement burrs cost more than the three times the Wilfa itself. High precision burrs that have a big surface area should lead to that magical thing we all chase in coffee, a uniform grind size,  which leads to an even extraction ! So we thought we’d buy this particular customers unit back from the distributor and test if it was indeed "NO GOOD FOR FILTER COFFEE" and compare it's grind size evenness against some of the grinders around the roastery to see if this workman in question really could blame his tool.

Contenderrrrs READY!

Let's start by defining a few important things:

  • Fines are particles of coffee that due their large surface area are eroded by the water lot quicker than particles of a larger size, this means their flavour is instantly accessible and will over extract a lot quicker than particles of a larger size. They also slow down the flow rate of the water passing through the brew, ever had a v60 choke up and the water stops flowing through? Yup that’ll be the fines. The particle size definition of a fine is smaller than 100 microns, however in this experiment I've classified fines as smaller than my desired range of particle size that’s meant to the optimum for v60 brewing.

  • Boulders are large particles of coffee with a small surface area causing them to hold on their flavour much longer than fines. Water finds it hard to erode the compounds leading to under extraction. In this experiment boulders where measured above 800 microns.

  • The optimum particle size that shall be measured for the test  will be between the ranges of 400 and 800 microns 

So why does this all matter? The more uniform the grind size produced by a grinder, the more even the extraction process will be. A brew made with a dose that’s heavy in boulders would be under extracted lacking in body and lacking flavour. A brew with a lot of fines would be technically over-extracted leading to bitterness and astringency in the cup. 

Introducing the contenders:

  • Wilfa Svart grinder the go to home brewers entry level grinder – price from £90 to £105 (from Norway).
  • Commadante NitroBlade C40 Hand grinder – One of the best hand grinders on the market that lives in Lewis’ Kitchen Price £180 - £200 (from Germany).
  • Mahlkonig EK43 – The go to speciality coffee filter grinder. Price £1800 - £2000 (made in Germany).
  • Ditting KFA1201. A bulk coffee grinder with 120mm burrs that was made in 1965. It's a beast.

The price difference in these grinders should make this test pretty self explanatory, the EK43 is going to be the best right? With the help of the Kruve particle sifter we’re going to find out!

The Test

Each grinder is going to be used to brew a V60 with a total brew time of 3 minutes with an error window of 5 seconds either side. A recipe of 15g of coffee to 250ml of water shall be used. A BWT Bestmax Premium filter will provide the water. Once each grind setting has been dialled in on all grinders, each individual dose will be sifted with the Kruve, a sieve that allows the separation of particles allowing undesirable particle sizes to be removed from the dose. Kruve recommend the 800 μm & 400 μm sieves for brewing V60. After brewing the TDS will be measured and all brews blind cupped to see which grinder produced the tastiest brew. TDS (Total Dissolved Solids) is the percentage of the coffee that has been extracted by water. Approximately 35% of the mass of a coffee bean is water soluble. In theory the closer we get to the 35% the tastier our brew will be right ? Well it's not quite that simple due to the make up of the compounds and various rates of extraction of these compounds, but yes in theory, the more we can extract the more flavour potential we have. At the moment due to traditional coffee grinder burr designs and their grind uniformity the maximum extraction percentages are around 23% before unpleasant characteristics become apparent in the cup.

  

The Results! 

Grinder Brew Time   Fines < 400 
μm (g)
Boulders > 800 μm (g) Optimum (g) TDS%
Wilfa 3.05 1.1 9.1 4.4 19.95
Commandante 3.00 1.1 7.7 6 19.51
Ditting 3.05 1.4 8.1 5 19.21
EK 43 3.03 0.6 11.2 2.7 15.69

 

 

After the blind cupping the results are as follows:

The winner..... It was a close call but the blind cupping led to the Wilfa coming out on top followed by the Commandate a close second. The Wilfa brew was juicy and had great body while the Commandante was super clean but just lacked the roundness in the cup. Our EK was straight last leaving us scratching our heads as to why our top end grinder had been outperformed by a £100 grinder! 

The EK produced far more boulders than any other grinder in the test, causing the brew to have the lowest TDS% leading to an under-extracted thin brew. The Wilfa produced the highest TDS% also leading to the the tastiest brew on the table. 

One of the reasons we feel our EK has underperfomed in this test, is due to the burr alignment. Misaligned burrs (we're talking microns here) causes grind size to be uneven. Our EK is the latest brand new version (EK43s) and the burrs have been radially aligned but not axially aligned. The fact a grinder that costs upwards of £1500 is required to have tin foil strips stuck underneath the burrs to align them is absurd ! Sort it out Mahlkonig !

The whole purpose of this test was to find out whether our customers claims about their Wilfa unit not being suitable for filter brewing where true, and as we can see they're clearly not! The figures don't lie and neither did our tastebuds. I have a few thoughts about why they weren't able to get on with their unit:

  • Most likely they where using the European made V60 papers (shrink-wrapped). These papers are horrific ! Hario changed trheir manufacturing methods with these papers which constantly choke and cause awful flat brews. Check the James Hoffman video on the different styles of Hario papers here and avoid the shrink-wrapped ones at all costs.
  • The coffee they where using wasn't soluble (poorly roasted).
  • Maybe they actually didn't know how to brew coffee properly? That's a little harsh I know especially since the customer 'works' in coffee.

Further conclusions from the results have led us to take a long hard look at our EK and try and get it up to standard, reviewing my remark “ what was he expecting an EK for £100!?”  The customer actually received a grinder that outperformed our EK in the roastery. A round of applause for Wilfa, the £100 home filter grinder that outshone the modern standard of filter grinders in the speciality scene.

Feel free to drop me a line if you want to discuss these findings.

lewis@crankhousecoffee.co.uk


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