The word is probably originated from the French word "lessive"
It was extensively used for washing clothes. The potassium carbonate in the water (that comes from the ash), has the property of dissolving oils and fats and therefore help to clean the clothes.
Alousiva was also very used in the kitchen and as a "soap" for hair and body wash.
In Cyprus, the word Alousiva is also used until our days to denote bad and lukewarm drinking water.
You can see this exhibit up close, along with many others, in the 1st-floor exhibition room of CVAR.
