One of the newest trends among espresso lovers has been the widespread adoption of WDT. If you have ever seen someone bent over an espresso puck with a needle or funny-looking stirrer, then chances are they are doing WDT.
The Weiss Distribution Technique fundamentally involves stirring the espresso puck with extra-fine needles to increase extraction and decrease clumping.
Yet while this sounds highly technical, it is surprisingly easy and affordable. This article will dig into what WDT is, how to do it, and which WDT tool to opt for.
What is WDT?
James Weiss invented the Weiss Distribution Technique (WDT) in 2005 as a means to compensate for clumping in-home coffee grinders.
Basically, it involves getting ultra-thin needles (0.25-0.4mm) and stirring the ground coffee in the portafilter basket. It sounds ridiculous, looks ridiculous, and yet achieves unarguable results.
And the reason is that many home grinders (even prosumer models) produce at least some clumping and an uneven distribution within the espresso basket.
For example, if you grind directly into the basket, the grinds will form a mound of sorts with more coffee in the middle and less on the sides. So if you tamp directly, you will get an even-looking puck, but in reality, there will be more coffee in the center and less on the sides. This produces channeling that will be obvious if you are using a naked portafilter and detracts from the overall flavor of the coffee.
Enter the WDT tool. By taking the small and seemingly unnecessary step of stirring the puck, you will ensure a more even distribution of grinds for better extraction.
And the difference really is starkly noticeable. We found that when we started using our WDT tool, there was a marked difference in taste and shot flow. In fact, even with our Niche Zero (a highly proficient prosumer grinder), WDT allowed us to grind finer for greater extraction and sweeter flavor.
You really have to try it to believe it.
When you use WDT well, you cannot only see a decrease in channeling, but all else being equal, your shots should flow a little slower.Scott Rao
It would be remiss to neglect that it is also surprisingly satisfying to do. Certainly, it adds another step to the workflow that would be impractical in a cafe setting. However, this funny step adds to the ritual and experience of espresso brewing for the home brewer.
How to do WDT?
So, if the benefits of using WDT for espresso are proven and indisputable, how do you actually do it?
This seemingly innocuous question has triggered a surprising amount of conversation among espresso enthusiasts.
The short answer is that if you are just starting out, then it is best to place the WDT tool right to the bottom of the basket and swirl in small circles until the puck is aerated and even. Make sure you cover all the areas of the puck.
It is generally agreed that less is better, so don’t overdo it. However, almost any WDT will improve extraction.
So give it a try, and don’t be afraid to experiment.
From a more technical perspective, there are basically three different forms of WDT, deep WDT, shallow WDT, and puck raking. It must be prefaced that the differences between these techniques are often seen in flow profiling (such as with the Decent espresso machine) and won’t be noticeable for the beginning brewer.
Deep WDT places the needles right to the bottom of the basket and stirs in overlapping circles until all possible clumps are touched. Shallow WDT just scrapes the top level of the ground coffee to even it out without going deeper. And puck raking, advocated by Decent inventor John Buckman, is similar to shallow WDT and involves gently flattening out the mound of ground coffee.
In a highly technical paper, astrophysicist Jonathan Gagne compared these methods and their effect on puck resistance. And his findings were that stirring right to the bottom of the puck (Deep WDT) led to an overall higher puck resistance and is consequently more effective than the other methods.
So don’t be afraid to go deep.
What is the best WDT Tool?
So if it works, if it is doable for just about anyone, how and where do you get one? And there are basically three options for getting a WDT tool; make a homemade one, 3D print one, or buy one.
And the reality is that any of these options can work as effectively as the others. So it comes down to convenience, cost, and personal preference.
Homemade WDT tool
The first option is to DIY it. And this is surprisingly easy to do. While people simply used a needle or hairpin or paper clip in the past, these are really all too thick for the purpose. Again, after multiple studies, there is a consensus that a WDT tool should use needles anywhere from 0.25-0.4mm for optimal effectiveness.
So if you are going to DIY it, you need to get your hands on the right size needles. The easiest way to do this is to buy Acupuncture needles. You can buy them on Amazon here.
Once you have your needles, simply insert anywhere from 3-6 into a cork top, and you have your WDT device.
3D printed WDT Device
The next option and the one we opted for was the 3D printing option. Obviously, this will depend on your accessibility to a 3D printer.
This option also requires the purchase of correctly sized acupuncture needles. From there, you simply download the free files and then 3D print them. This is the same one that was 3D printed and advocated by James Hoffman.
After that, you simply insert the needles, screw the two pieces together, and you have a superb WDT device. This is certainly our preference and is highly satisfying.
You can then paint it if you see the need or leave it the color of the resin used.
Purchase a WDT Device
The final option is far less hassle and involves simply buying it. There is a range of different WDT models on the market these days, many of which are more than sufficient.
However, as a simple google search will reveal, there are as many models as there are leaves on a tree. So basically, find one that appeals to you and has needles not exceeding 0.4mm, and you will be away laughing.
WDT – In Summary
In summary, we highly advocate the WDT method. It is easy and satisfying to do, and noticeably impacts grinds distribution and extraction.
It is probably the cheapest way we know of to INSTANTLY improve the quality of your espresso. So hunt down a WDT tool and try it for yourself. I can promise you won’t look back.