tags: [] - coffee/processing aliases: - Wet processing - Fully washed process - Washed method

Wet Process¶

Tags: #coffee/processing Aliases: Wet processing, Fully washed process, Washed method Related: Coffee Processing MOC | Washed Processing | Fermentation | Wet Mill | Natural Processing Status: ✅ Complete

Overview¶

The wet process — synonymous with washed or fully washed processing — is the method of preparing coffee for export in which the fruit skin and mucilage are removed from the coffee seed by mechanical depulping and water-assisted fermentation before the parchment coffee is dried. It is called "wet" because water is used extensively in washing away fermented mucilage residue after fermentation; this distinguishes it from the natural (dry) process, in which the whole cherry is dried without water. The wet process is the most widely used method for specialty arabica production globally, producing clean, bright, terroir-expressive cup profiles.

Process Steps¶

Receiving and sorting: Ripe cherries sorted by density (flotation); underripe and defective cherries removed
Pulping: Depulping machine removes the outer skin (exocarp), exposing the mucilage-coated parchment
Fermentation: Parchment coffee placed in tanks or piles; naturally occurring microorganisms break down the pectin layer of the mucilage over 12–36 hours (aerobic or anaerobic)
Washing: Fermented mucilage is washed off with clean water in washing channels; the wash test (clean, gritty feel of the parchment) confirms complete fermentation
Grading channels: Parchment washed through channels allows further separation by density; damaged or defective parchment floats out
Drying: Parchment coffee dried on raised beds or patios to 10–12% moisture, typically 10–20 days depending on conditions
Milling (hulling): Dry parchment removed at the dry mill; green beans sorted, graded, and packed for export

Cup Profile¶

Washed coffee produces a characteristic cup profile: - Clarity: The direct expression of origin, variety, and altitude without fruit overlay - Bright acidity: Organic acids preserved and expressed clearly - Clean cup: Minimal fermentation character; defects more detectable due to lack of fruit masking - Light to medium body: Less mucilage contact means less sugar/body development compared to natural/honey - Terroir expression: The most transparent processing method for evaluating origin character

Water Use¶

The wet process is water-intensive: traditional wet mills use 40–45 litres of water per kilogram of parchment coffee. Environmental concern about wastewater (called "pulping water" or "coffee effluent," which is high in organic acids and BOD) has driven adoption of eco-pulpers that reduce water consumption significantly.

Key Facts¶

Wet process = washed/fully washed processing; water used to remove mucilage after fermentation
Steps: sorting → depulping → fermentation → washing → drying → milling
Produces the cleanest, most terroir-transparent cup of any processing method
Traditional wet mills use 40–45 L water/kg green; eco-pulpers reduce this significantly
Most common processing method for specialty arabica in Colombia, Kenya, Ethiopia (washed), Central America

Washed Processing
Fermentation
Wet Mill
Natural Processing
Honey Processing (Coffee)
Coffee Processing MOC

References¶

Changelog¶

Date	Change
2026-04-28	Note created

This article is part of All-About-Coffee.com - The comprehensive coffee knowledgebase.