Percolation

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Percolation Mechanics

P 1.07 Drawdown

Drawdown

 

The final phase in the mechanics of brewing is the drawdown. With mechanical brewing and pour-over, this phase initiates after the final addition of water. Any intervention into the coffee bed is not possible with most mechanical brewers. With pour-over coffee, however, many baristas elect to perform a final agitation of the coffee bed to level it out at this point. There is a range of approaches for this, but as a general rule, BH doesn’t advocate agitating into the coffee grinds. This has the effect of causing an excess of fines migration, which can cause a severe blockage of the pores in the filter paper below.

 

In this video, Matt demonstrates the effect of excessive agitation of the coffee bed on a brew dialled in for a 3-minute contact time. You will notice the total contact time draws out to several minutes longer than the recipe.

 

 

 

The Rao Spin

A method popularised by renowned coffee educator Scott Rao is to take hold of the filter cone and manually rotate it, creating a gentle whirlpool in the slurry. This can be very effective in creating a flat coffee bed and is particularly helpful in faster pour-over methods that involve only two pours. (See Lesson 3.04) Here is Scott in action explaining his method.

 

 

NSEW

A repeatable means of creating a level bed is one similar to the process we suggest for blooming your coffee. With the help of a spoon or spatula, it involves a north–south motion with two or three repetitions, followed by the same motion from the east–west (hence, ‘NSEW’). This can be a very repeatable and fast process, with the drawback that it requires you to handle another tool, so it is a little less efficient than the Rao Spin. Except for during the blooming process, Barista Hustle does not endorse the practice of stirring into the coffee bed for any agitation of the brew.