![]() ![]() “Gagne’s results are convincing, but the improvement going to the bottom is slight”. While deep WDT may be more effective, both techniques are effective compared to other distribution methods, and puck raking is easier, Buckman argues. This suggests that deep WDT is more effective than puck raking. He found that stirring right to the bottom of the puck led to higher puck resistance overall, and more importantly, less variation in the resistance from one shot to the next. In a recent White Paper published on Barista Hustle, coffee blogger (and astrophysicist) Jonathan Gagne compared the two methods, using puck resistance as a measure of how effective the technique was. There is debate about whether it is preferable to stir only the grounds at the surface, sometimes called ‘ puck raking’, or to stir right to the bottom of the basket, referred to as ‘deep WDT’. “ It’s easy to cause uneven density throughout the coffee bed if you do WDT sloppily or too aggressively,” Rao says. It’s also important to stir carefully and evenly throughout the bed. Our testing has shown that anything more than 1mm in diameter is counterproductive, so a toothpick, for example, would not be suitable. The first consideration when adopting WDT is using the right tool. “In the cup, using WDT should decrease the average amount of bitterness and astringency, and should make shot times and extraction levels less variable,” Rao says. The real test is the flavour and consistency of the shots made using the technique, however. ![]() “The improvement in shot quality is obvious.” “ With WDT, we can see shots have a higher peak pressure and sustain it longer,” writes John Buckman, the inventor and owner of Decent Espresso. In a flow profiling machine, higher resistance leads to higher pressure at the puck. Increased resistance in the puck is an indication that the particles are packed more closely together, which is a key characteristic of a well-distributed puck. “When you use WDT well, you cannot only see a decrease in channelling but all else being equal, your shots should flow a little slower, which is a side effect of decreased channelling.”Ĭhannels can be detected by looking at extraction curves. “The most compelling evidence for the efficacy of WDT is reduction in channelling,” Scott says. Several manufacturers sell tools like this one, designed to make the Weiss Distribution Technique easier and faster. We asked him what it was that convinced him that the WDT was the most effective distribution method.Ī WDT tool. Perhaps the person most responsible for bringing discussions of WDT back into the mainstream is Scott Rao, who used versions of the technique as part of a strategy to achieve very high extractions. By this measure, the WDT seems to be highly effective. By measuring pressure and flow inside the puck, we can see which techniques produce a more stable puck, and which are more prone to cause microchannelling. More recently, the detailed analysis of espresso techniques made possible by pressure or flow-profiling machines like the Decent, have brought the WDT back into the limelight. For this reason, and also because of the time it adds to the workflow, the WDT is very rarely used by professional baristas. While some grinders achieve this more effectively than others, it was generally thought to make the WDT unnecessary. The WDT became well-known among home baristas, and has been written about extensively in the years since.Ĭommercial and ‘prosumer’ grinders generally include features designed to break up large clumps and distribute the coffee more evenly into the basket, directly from the grinder. The WDT is named for John Weiss, who developed the technique back in 2005 as a way to compensate for grinders, especially smaller home grinders, that produced excessive clumps. The Weiss Distribution Technique in action. The result is reduced channelling, and higher, more even extractions. The stirring action breaks up any clumps, and evens out the density of coffee within the puck. A funnel placed above the portafilter helps prevent spills. Using a fine needle or similar tool, the barista stirs the coffee while it sits in the portafilter. The Weiss Distribution Technique (WDT) is a distribution method for espresso making. Should we all be using the Weiss Distribution Technique again? Is there a right way and a wrong way to do it? ![]()
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