This morning I decided to put the Ross droplet technique (RDT) to the test and see if it is as effective at addressing static and grinds retention as I was led to believe. I wouldn’t say I was a skeptic, but certainly I had never had any need for, or interest in, trying it out. I saw a good discussion on Home Barista about using the method on some other grinders and was impressed with the before and after photos people had shared.
I dug out the oldest bag of coffee I could find. It’s a sample roast which had been inadvertently baked during roasting – it was dry and brittle. I also turned up the central heating in the house to dry things out. I recently learned that static is more apparent with lower humidity.
Oh, man! I hit the jackpot on my first grind with an incredible amount of coffee ending up everywhere but down in the cup. I then tipped as much coffee as I could get from the first cup, into a second cup and weighed the result. There was still enough static that some coffee remained stuck in the first cup. Of the 16 grams I put in the grinder, only 11 ended up in the final cup. That’s 30% retention! You can see the result in the top half of the photo below. I had never seen anything like this with the coffees I had tested before.
The next step was to try another grind with the Ross droplet technique. I used the same amount of beans (16 grams), but this time I dabbed a tiny bit of water on top of the beans as they sat in the grinder hopper. I really didn’t add very much. I used one finger, shaking off most of the water before touching the beans. I dipped my finger in the glass of water 3-4 times, then touched the beans 2-3 times per dip, leaving very small droplets on a few beans.
Seriously, I could not believe the end result. After weighing the output, I found that for the 16 grams I put in, I got 16 grams out. It’s quite possible some of that was retained grinds from the previous attempt. I also don’t know whether the small amount of water I added weighed enough to register. In any case, the difference between the two attempts was night and day – see the bottom half of the photo above.
After that, I ran five more tests with increasingly fine grind settings and for the most part, the results were the same. On one occasion I consciously used slightly less water, and saw a little more static and 1 gram of retention.
Overall I’m blown away by how effective the Ross Droplet technique is. I imagine it would be as effective on other manual grinders where static is an issue. I’m sold.
Here’s a video from Patrick, the ROK grinder’s designer, demonstrating the Ross Droplet Technique: