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Coffee Processing Method

Wet Hulling

Also known as: Giling Basah

Wet hulling is Indonesia's signature method, born of Sumatra's humid climate where fully drying parchment is nearly impossible. Coffee is pulped, briefly fermented, part-dried to 30–35% moisture — then hulled while still wet and soft, and finished as bare green beans. No other origin routinely dries naked green coffee.

The method stamps an unmistakable identity on the cup: earthy depth, cedar and spice, herbal savoriness, and heavyweight body with muted acidity. It also explains Sumatran coffee's distinctive bluish-green bean color and the slightly higher rate of physical defects, since soft wet beans are vulnerable during hulling.

How the wet hulling works

  • Pulping at the farm, often with small hand pulpers
  • Short overnight fermentation and rinse
  • Partial drying to 30–35% moisture
  • Hulling while wet ('giling basah') at a collector or mill
  • Final drying of bare green beans to 12–13%

Wet Hulling at a glance

Flavor impactEarthy, cedar, dark chocolate, herbal savory notes; heavy syrupy body with low acidity — the classic Sumatra profile.
Key risksHigher physical defect rates and mold risk if the naked-bean drying stage is rushed or rained on.
Water useModerate — pulping and a short rinse.
Drying timeSplit across two stages; typically 5–10 days total in Sumatran conditions.

Origins known for wet hulling

Wet Hulling — frequently asked questions

Why does Sumatran coffee look bluish-green?

Hulling at high moisture exposes the bean surface while it still contains chlorophyll-rich moisture, giving wet-hulled lots their characteristic dark bluish-green color that buyers use as a visual signature of the process.

Is wet-hulled the same as washed?

No. Washed coffee dries inside its protective parchment to 10–12% moisture. Wet-hulled coffee has the parchment removed at 30–35% moisture and finishes drying as naked green beans — a fundamentally different flavor and handling profile.

Does wet hulling lower quality?

It trades some cleanliness and raises defect counts, but the profile it creates — heavy body, earthy spice — is exactly what buyers of Mandheling and Lintong coffees demand. For that market, the process is the quality.

Volcana Coffee produces washed, natural, and honey-processed lots on the Bolaven Plateau, Laos, with controlled fermentation and SGS-verified quality. Ask for our current processing menu and cupping samples.

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Other processing methods

Washed Process

Clean, articulate cups with bright acidity and clear varietal character.

Drying: 6–12 days on raised beds depending on weather.

Natural Process

Heavy body, intense berry and tropical fruit, lower perceived acidity, wine-like sweetness. Signature profile of Ethiopian and Brazilian naturals..

Drying: 14–30 days depending on climate and bed loading.

Honey Process

Rounder body and more sweetness than washed, cleaner than natural.

Drying: 10–20 days; darker honey grades dry slower by design.

Anaerobic Fermentation

Amplified sweetness and exotic notes — cinnamon, red wine, tropical punch.

Drying: Follows the finishing style: 10–25 days.