How nori is made

Nori sheets are made much like paper: seaweed is shredded, spread on screens and dried.

stations: 6
things upstream: 1
raw source: 1
step from the ground: 1

The short version

Nori is grown on nets suspended at the sea surface. Farmers harvest the red seaweed by machine every ten days or so, chop it into a slurry and spread the slurry onto screens in a process much like making paper. The thin sheets are dried on racks, then often toasted. A desiccant keeps them crisp in the pack.

Seed the nets

Nori farmers seed nets with young Pyropia and suspend them at the sea surface, working from boats. About 45 days pass before the first harvest.

about 45 days to first harvest
Harvest by machine

Mechanical harvesters cut the blades from the nets. A single seeding can be harvested repeatedly, about every ten days.

about every 10 days

Goes in
Seaweed
Chop to a slurry

The seaweed is washed and shredded into small pieces in water.
Spread onto screens

Automated machines pour the seaweed slurry onto flat screens in thin layers, a mechanical copy of the hand method, which was borrowed from Japanese papermaking around 1750.
Dry on racks

Racks of screens carry the wet sheets through drying. What comes off is a paper-thin, black, dried sheet.
Toast and pack

Sheets are often toasted and sometimes seasoned with soy sauce, sugar and other flavors. Because nori soaks up moisture from the air and degrades, packs include a desiccant.

End of the lineNori

Worth repeating

Japan's nori industry was rescued after World War II by the work of British phycologist Kathleen Drew-Baker, who had unraveled the seaweed's life cycle.
Japan devotes more than 600 square kilometers of coastal water to producing 350,000 tonnes of nori.
Nori was used as currency in Japan and counted as a form of taxation in the Taiho Code of 701.