Spoiler, its RDT
In case people do nto know what RDT is, which they really should if they have been into coffee for a little while as it makes a big difference:
RDT is Ross Droplet Technique, which is very much adding water to beans. Named after David Ross who came up with it back in 2005
How does wet beans not gum up the mill?
You add a very very small amount of water. Like one spray from a tiny spray bottle.
If you make them that wet you are doing it wrong, lol.
You only need a drop or two of water for espresso and only slightly more for a larger amount of beans for a pour over, it’s a tiny amount. People have been doing this since 2005 without problems.
Check out: https://www.youtube.com/watch?v=GuqVUsMPs-U&t=2620s
If you don’t believe me
Ok, thanks. I’ve got a decent mill with a hopper. Would something as simple as suspending a damp sponge in the hopper be sufficient to raise the moisture content to reduce static charge or does it have to be physically applied to the beans to be effective?
I wouldn’t recommend that approach, its more suited to single dosing, which is based around grinding only the amount of beans you need for that single lot of coffee by only feeding the hopper with the amount of beans needed rather than using the hopper for bean storage.
So weighing out your beans first for a single espresso or pot of pour over, wetting those beans with a drop or two at most of water, giving them a shake/stir, then feeding them into the hopper and making sure everything comes out that you put in.
Single dosing makes it easier to get the exact amount of coffee by weight each time from cheaper grinders and can lower retention (how much ground coffee the grinder holds in its burr chamber and spout) when combined with RDT and flushing out the grinder with something like bellows and discarding what comes out as its mostly chaff and fines that you do not want. Coffee tends to build up even in expensive grinders without flushing it out, this goes stale over even a few hours and works its way into your normal cups of coffee.
Grinding by weight is still pretty limited availability, most with a hopper tend to offer grinding by time, which is nowhere near as accurate. Grinding by weight makes it easier to make your coffee more predictable, its especially important for espresso as you are trying to fill the basket almost but not quite the top. Espresso is better measured by volume as coffee density varies by roast type and by time since the beans were roasted, but that is much harder to do than by weight on a regular basis so most people just use weight.
