What is the WDT tool?
If you’ve been paying close attention to a barista over the past decade, you may have noticed some changes in their espresso-making habits. After filling the portafilter with coffee and before tamping the espresso, many baristas have added another step – distributing the ground coffee using a gadget known as a WDT tool (Weiss Distribution Technique).
This spiky handheld device looks like a little open-ended whisk, or maybe one of those scalp irritating things… but for espresso. This handheld tool, available in a variety of shapes and styles, has been recognized in the industry as the best way to prepare a dose of espresso for extraction by evening out the way the grind is dispersed throughout the portafilter. This is done to reduce the paths that create water channels and uneven extraction to make your espresso taste better.
Where did this catchy name come from?
The Weiss distribution technique and its associated tool are named after John Weiss, a biomedical and computer science researcher who is also an espresso enthusiast. In 2005, Weiss began making the perfect espresso, inspired by an early 2000s phenomenon then called “espresso porn” (don’t Google it): the trend of photographing lush, tiger-striped espresso dripping from bottomless flasks.
“I wondered why some pours were stunning and others looked like shit,” says Weiss, who concluded that the problem was uneven extraction due to the uneven distribution of the coffee grounds.
To test his extraction/distribution theory, Weiss first looked at the tools he had at home. “I still had the dissection kit from college, so I tried using the dissection needle to mix the pulp.”
“It was also helpful in breaking up lumps,” Weiss says, which was a common problem with early dosageless grinders. “I don’t know who came up with the idea of adding more needles, but it was a good idea to speed up distribution.” He connected the needle to a homemade dispensing funnel – made from a recycled yogurt cup – to reduce the mess while raking the dirt.
Weiss began sharing his method on coffee enthusiast message boards, and the rest, like uneven distribution and unpleasant channeling, became history.
Wow! Has John Weiss invented any other coffee products?
“If I had it to do over again, would I focus more on coffee research? Hell yes!” says Weiss. “At the time, it just seemed like a fun hobby. But looking back, my silly WDT article got far more attention than any of the 80-plus research papers I’ve published in fields as diverse as biochemistry, neurobiology, climate modeling, and artificial neural networks.” In the field of coffee, Weiss recently created software for extraction analysis Decent espresso machines.
What WDT styles are currently available? Have other options developed in recent decades?
There is a truly stunning array of WDT options these days, ranging from high-end tools such as Duomo Or Moonraker just grab a few paper clips from your desk. There are now also other tools that can be used alone or in series with a WDT tool, such as wedge splitters or even stock vibrating devices.
The desired style of WDT tool often depends on the employ case. We turned to Coffee with a monogram co-founder and seven-time Canadian barista champion Ben Put for insight.
“We employ Autocombs in our cafes, they are the fastest and most hard-wearing and least susceptible to needle bending,” says Put, who notes that at Monogram not all espresso drinks are marked with WDT. “We’re trying to come up with drinks based on hierarchy – when will you taste them?”
Put says that for any drink smaller than a cappuccino, Monogram baristas employ the WDT tool. “These coffees are a bit more fruity and adventurous, but we assume customers are a bit more demanding, so we only employ WDT for that.”
While you’re here, does Ben Put think WDT tools are indispensable for barista competitions?
“It’s a regular part of my coffee preparation,” says Put, who claims to have tried almost every tool available on the market. “I used the Moonraker on stage quite a bit because the needles follow a different path than just a circle.” Include notes that competition results include points for both appearance and technology, which may impact the employ of the WDT tool in competition procedures.
“I think there’s definitely an improvement over doing nothing, but I don’t know if that’s a silver bullet,” Put says. “They are baristas for many reasons [at world championships] they employ it to make sure they get a good result on the technology.” Put notes that 2025 world barista champion Jack Simpson used a WDT tool and then a vibrating plate to settle the espresso grounds. Put considers this extra step as “a compass pointing us in the right direction.”
But do I really have to deal with all that coffee tamping? Will a good enough grinder one day eliminate this step?
As grinders improved, the problems solved by the Weiss distribution technique decreased. However, many baristas still insist that using this technique – and tool – is the best way to ensure a well-rounded shot. As with the Simpson vibration plate, the evolution of technology goes hand in hand with our understanding of needs.
“I think WDT is calling attention to the fact that the density of our coffee is not equal,” Put says, “but I think it’s the beginning of understanding coffee density, not the end.”
