RDT (Ross Droplet Technique)
also: Ross Droplet Technique, spritzing beans
Adding a drop or two of water to beans before grinding to cut static and retention.
RDT, the Ross Droplet Technique, means lightly wetting your beans with a single drop or two of water (or a quick spritz) and stirring before you grind. Named after a forum user, Ross, it is now a near-standard habit among espresso home users.
Why it matters: dry beans build up static charge as the burrs shear them, especially with very fine espresso grinds. That static makes fines and grounds cling to the grinder, the chute, and your dosing cup, spraying mess everywhere and leaving coffee stuck inside (called retention). A tiny bit of moisture grounds the charge, so the grind drops cleanly with far less clumping and static cling.
The amount is genuinely tiny: a drop or two on the whole dose, not a soak. Too much water can cause clumping or, over time, corrosion concerns in some grinders, so keep it minimal. RDT pairs naturally with WDT in a tidy dialing workflow: RDT keeps the grind clean coming out, WDT distributes it evenly in the basket. It also makes consistent dosing easier because less coffee gets left behind shot to shot.