Cut Down on Your Coffee Grinder Mess With Just a Drop of Water

I love iced coffee unconditionally. But, until recently, I had a tempestuous relationship with my coffee grinder. The grinder is a very nice burr-style model, the well of which holds a full bag of beans. I can easily change the amount of coffee I grind each morning, depending on that day’s caffeination needs. Basically, it’s as nice as a coffee grinder can be.

And yet: Every time I pulled the ground coffee receptacle out of its cubby after grinding, the air around me would be set adrift with ephemeral wisps of coffee bean husk (technically called the silverskin, which is usually removed during processing but some of which can stubbornly cling to the bean even after roasting). A few papery flakes would cling to the machine, held there by static. The remainder would be strewn around the table—behind, in front of, and all around it too.

But that all stopped the day I learned about the Ross Droplet Technique (a.k.a. RDT), which sounds very technical, but amounts to this: Add a single drop of water to your unground beans, stir it around with your finger or the handle of a spoon, and grind. Not to get too into the science of it, but static electricity is caused by an imbalance in positive and negative charges; a cold environment or one with low humidity can make those opposing forces worse. Adding a small amount of moisture increases the humidity in the grinder. This idea was allegedly first proposed in a 2005 online coffee forum by one David Ross, although the original thread appears to have been lost to the sands of time. While the origins of the technique are somewhat hazy, the results are undeniable. After my first round using the RDT, the ground coffee came out in a tidy pile with no wisps anywhere in sight. In fact, the method was so simple, I figured I must be missing something, so I reached out to a couple of experts to make sure I wasn’t doing any damage to the machine (or to the beans).

“Every situation is different,” says Sahra Nguyen, founder of Nguyen Coffee Supply. When you factor in conditions like “weather, heat, and humidity in the home,” you may need a little more or a little less water for the method to work properly. Both Nguyen and Nick Terzulli, the director of mechanical engineering at Fellow, agree, however, that any amount of water you use should be minute.

Terzulli likes to use the spoon method: Run the handle of a spoon under water—he says “you only need one or two drops of water.” Then stir a single dose (15 to 80 grams) of whole coffee beans with the handle. He’s also a proponent of the spray method: Using a miniature spray bottle, spritz a single dose of beans once or twice, then stir or shake beans to distribute before grinding.

Nguyen favors the finger method: Dip one finger into a cup of water, wave your finger over a single dose of beans three times, and then use a dry finger to mix the beans and water droplets together. She says “this finger-waving technique adds about 0.1 gram of water to the beans” and that “if there is still static, you may need a fourth wave.”

You’ll love iced coffee even more when you don’t have to vacuum up after it.

Photo by Chelsea Kyle

The type of water you use doesn’t matter much, but Terzulli usually opts for filtered. You should aim for tepid water, however, or water that’s the same temperature (ideally room temperature) as the beans you’re using.

Neither expert recommends using this method for a larger batch of beans, or for beans you don’t plan on grinding right away. “Any water contact is technically beginning the extraction process,” Nguyen says. “If you’re not brewing [the beans] and drinking [the coffee] right away, then you’ll be missing out on some part of the experience. Will you notice the difference in flavor and taste? That’s a personal determination.”

Terzulli notes that “because water evaporates over time, using this method may work great on day one for [a larger stash of] beans in your hopper, but by the next day, your results will not be the same. Plus, keeping coffee wet for extended periods of time is not recommended.”

My take? I’m going to keep dispensing a full bag into my grinder’s hopper and adding one or two drops of water before each grind. For me, it’s worked like a dream and the taste of my morning cup hasn’t suffered any for it. And since my grinder measures my coffee each day so that I don’t have to, that means I’m a step closer to the cooling bliss that helps me wake up most mornings—a lot less cleanup required.

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