Efflorescence Test (IS: 3495 (Part III)): The ends of the brick are kept in a 150 mm diameter porcelain or glass dish containing 25 mm depth of water at room temperature (20° - 30° C) till the entire water is absorbed or evaporated. The water is again filled to 25 mm depth in the dish and allowed to be absorbed by the brick or evaporated. The specifications limit when the deposit of the efflorescence to be not more than moderate (10- 50%) or (more than 10% but less than 50%)up to class and not more than slight (< 10 per cent) for higher classes.