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Percolation Mechanics

P 1.08 Recap and Glossary

1.08 Recap and Glossary




  • The specific heat of a brewing device should be considered when preheating.
  • Unbleached filter papers impart a cardboardy taint to brewed coffee.
  • Rinsing filter papers helps to remove residues of dissolved lignin from filter papers.
  • Aromatics total less than 0.4% of the total gas content of roasted coffee.
  • BH has measured a 20% loss of roasting gases just one minute after grinding coffee so it is essential to grind and brew immediately.
  • Coffee grinds should be horizontally levelled before brewing.
  • Hand brews require manual agitation to ensure all the coffee bed is saturated simultaneously.
  • The birdsnest technique can help to guide brew water down to the bottom of the coffee bed during blooming.
  • The height and flow rate you use when pouring affects the level of turbulence you create.
  • Pouring with a directional-flow will create an uneven coffee bed unless you compensate with some manual agitation.
  • Orbiting the coffee bed can help to disperse the turbulence more evenly.
  • The final phase of the brewing cycle is called the drawdown. This phase requires a level coffee bed.
  • Level coffee beds can be achieved with the Rao Spin, or the NSEW technique.
  • Agitating into the coffee bed seems to promote fines migration which has the effect of elongating drawdown times.




Acrylic  a type of hard transparent plastic

Blooming  the prewetting process used at the beginning of the brew cycle in percolation coffee brewing to ensure all the grinds are evenly saturated with brew water

Breaking the crust  The method of agitation used in the cupping method to ensure all the grinds are submerged beneath the surface of the slurry of brew water and grinds.

Brew cycle  the amount of time the water takes to pass through the coffee bed

Brew water  The total amount of water used for extracting coffee grinds

Clumping  (Clumps) The unintended packing of grinds to form small chunks

Conductor  A material that allows electrons to move freely through it.