One simple test of the success of your prewetting method is to note how long it takes for bubbles to stop rising to the top of the slurry during prewetting. Each time you see a bubble appear during prewetting, it indicates a dry area of the coffee bed just got wet and released some carbon dioxide. If bubbles form over the course of one minute, it means some areas of the coffee bed did not get wet for a full minute after prewetting began. In addition, consider that the last grounds to get wet were likely wetted by liquid packed with coffee solids; such liquid is a poor solvent. On the other hand, the first water to contact the grounds during prewetting is low in solids, and an excellent solvent. The net result is some grounds get a big extraction headstart , both in time and rate.

I recommend prewetting with careful agitation, such that no bubbles form more than 10-15 seconds after you begin pouring. It may be wise to use the minimum agitation necessary to achieve that goal, though, as too much agitation may cause fines to plug the pores of a paper filter.

Turbulence

Turbulence increases the rate of extraction and, if used wisely, can improve extraction uniformity. There are a few ways to increase turbulence during brewing: stirring, pouring at a faster rate or from a higher position, or spinning the filter. How to best utilize turbulence will vary depending on the brewing apparatus, but generally I recommend stirring during prewetting and adding a form of turbulence again as soon as you’ve finished pouring water on the grounds.

The Rao Spin

A couple of years ago I began noticing references online to various versions of something called the “The Rao Spin.” This intrigued me, as I hadn’t invented any of those methods, but somehow my name was attached to them. (There are other Raos in the world, but I’m pretty sure most of my relatives live in Southern Italy, drink robusta-laden espresso, and think hand pours are dishwater.)

Last year I walked into Aroma Caffe in Bologna, one of Italy’s rare third-wave cafes, and had one of most surprisingly wonderful coffee experiences of my life. Aroma (full name: Bar Aroma Degustazione E Vendita Di Caffe' Pregiati) is owned by one of the world’s nicest couples, Cristina and Alessandro. I asked Alessandro to make me a hand pour of one of Rubens Gardelli’s coffees (I forget which it was, but it was lovely), and Alessandro brewed a flawless extraction during which he spun the entire v60 after he finished pouring the brewing water. Alessandro thought it was quite funny that I’d never seen or heard of this method, given that it had been named after me. Here’s a 7-second video of Alessandro doing the Rao Spin:

https://www.youtube.com/watch?v=jopwfCGxj10

I don’t know why the Rao Spin works so well, but it minimizes channeling during the final drawdown and creates a flat spent bed every brew. It’s so good, I wish I had invented it :).

Note: I did invent a method involving a light thump of the brewer during the drawdown. It also decreases channeling, but I’ve come to favor the Rao Spin. Occasionally I will use both during a brew.

Channeling

A good batch brewer has a wide, flat spray head that disperses water more evenly over the coffee bed than can be done using a kettle. Pouring from a kettle is more likely to create channeling during wetting. Spinning or thumping the filter, pouring strategically, and using a coarse-enough grind can all help prevent channeling.

Which Hand Pour Method is Best?

To my mind, there are three main categories of percolation hand pours:

Cone-shaped filter (V60/Melitta)

Flat-bottomed filter (Kalita)

Steep-and-release (Clever)

Each has its strengths and weaknesses.

Cone filters (V60 and Melitta, etc)*