What is a coffee mill?

A coffee mill is a processing facility responsible for transforming coffee from its post-harvest state into exportable green beans. There are two distinct types - and understanding both helps you read supply chain documentation accurately.

Wet mills handle fresh cherry: pulping, fermentation, washing, and initial drying. They deal with coffee in its most perishable state and make the decisions most directly affecting cup quality.

Dry mills take over from there, receiving dried parchment or dried natural cherry and carrying out the final mechanical preparation: hulling, density sorting, screen sizing, colour sorting, grading, and packing for export. The precision of dry milling determines the defect count and consistency of what you actually receive.

In some origins these are separate facilities; in others they're combined on the same site. When a lot specification references both washing station and dry mill, it's describing two sequential stages in the same transformation.