Salt production method

Outline of salt production

Since ancient times in Japan salt has been produced using a unique method: by making salt concentrate (about 20% salt) from seawater as the first step, then by boiling down the concentrate to crystallize the salt. This method is necessary because there are no salt lakes or rock salt in Japan and because salt production using natural solar evaporation is not suitable in the Japanese climate of heavy rainfall and high humidity.

Taking seawater

Salt concentrate production process

Concentration of seawater

using salt fields (banked salt-terrace, channeled salt-terrace and sloping salt-terrace) or ion-exchange membrane electrodialysis.

Boiling-down process

Boiling-down salt concentrate

using earthenware salt-boiling vessels or salt-kettles (clay, stone and iron kettles) or a vacuum evaporation system.

Crystallization process

In addition to the above, salt is produced in Japan from imported sun-dried salt by dissolving and recrystallizing the salt or by grinding the salt.