Semi-washed covers a group of methods that sit between fully washed and natural, and the term is used loosely across producing countries.
The general shape
The skin is removed mechanically. Some of the mucilage is stripped off — often by a mechanical demucilager rather than by fermentation — and the rest dries with the bean.
There is little or no tank fermentation, which is the main departure from washed processing.
Why producers use it
Water. Full washing traditionally uses a great deal of it, and semi-washed dramatically reduces that.
Time. No overnight fermentation means faster throughput.
Consistency. Mechanical demucilaging is more controllable than waiting for enzymes.
The cup
Between the two poles: cleaner and brighter than a natural, sweeter and fuller than a washed. Less complex than either done exceptionally well.
The terminology problem
Semi-washed, pulped natural, honey and giling basah all overlap and are used inconsistently by region. Indonesian wet-hulling is sometimes labelled semi-washed and is a genuinely different process.
If a bag says semi-washed, the roaster’s description of what actually happened matters more than the label.
Brewing it
Versatile at medium roast. Filter and espresso both work.