Vacuum Pot Filtration

I’m impressed with the cleanliness of my vacuum pot’s coffee.  It leaves a lot less sediment as compared to french press, and that last swallow is tolerable rather than being nasty.  The reason a vacuum pot leaves less dust in the cup is that the coffee is pulled through a filter bed forrmed by the grounds.

This photo was taken immediately after the kickdown, the dusty scum is clearly visible on the sides of the bowl.

Light-colored dust is visisble on top
Light-colored dust is visible on top

Here I pulled out the rod from the filter bed, you can see how the dust stayed on the top layer.

Layers of dust and clean grounds
Layers of dust and clean grounds

Another shot showing the clean and dirty layers.

The darker, cleaner grounds are visible where the rod was removed
The darker, cleaner grounds are visible where the rod was removed

Compare this to a press pot where the grounds & dust remain suspended in a slurry underneath the plunger.  When pouring a cup the grounds aren’t compacted enough to form a filter bed and the metal screen certainly isn’t going to stop them.

There’s a strong analogy between this and a lauter tun (this is a beer site afterall).  The brewer takes care to form a good filter bed for the lautering process and the grain does most of the work keeping the wort clean.

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