The technique of slaking burnt lime has been described frequently in the historical literature. It becomes obvious that the burnt lime was not slaked by a wet technique, where the burnt pieces are kept in water over a long period. It is more probable that a dry technique was used, where the burnt limestone was just moistened by water, either by spraying water or by dipping buckets of burnt lime briefly in water. This technique seems to be responsible for the resistance of ancient mortars.