Efflorescence 4 : Chalklike appearance on a wall caused by evaporation and crystallisation of salts in the bricks and mortar. Chemically the word is used to indicate the loss of water from a crystalline hydrate exposed to air
H. J. Porter (Chairman - Technical Committee), Dictionary of Fire Technology, The Institution of Fire Engineers, The Victory Press (Leicester) Ltd. 1979 UK. (Fr Tech - Brit) {81}