9 History
Drying and burning the seaweed
Sec'hañ ar bezhin
Drying the seaweed
Once the seaweed has been unloaded, it is spread out on the dune to dry. That intended for burning may dry for up to three days depending on conditions. It is gathered into small heaps in the evening or at the slightest threat of rain, to protect it from the damp.
Pioka, which must be bleached before use, is first rinsed before drying, then spread out and turned regularly until it turns white. It then keeps for a year, away from light and damp.
Burning
A new technique developed in the 18th century: burning. Black seaweed and above all kelp were used. The seaweed ashes obtained, called ludu, were first used in farming, as a soil amendment.
Industry gradually made use of the compacted ashes known as soda cakes: the glass industry to begin with, then above all the iodine industry, which led to the proliferation of kilns along the coasts in the 19th century.