Theory 116/Coffee extraction/Threshold lens
Channeling Needs a Pressure Threshold
The claim
Channeling begins above a threshold in the ratio of pump pressure to bed permeability, so the same grind channels in one basket and not another.
01Mechanism
Water exploits the path of least resistance; the ratio determines whether it breaches the bed uniformly.
02Prediction
Channeling should track the ratio.
03Refutation
Channeling tracking pressure alone would remove permeability.