The volume of water required to slake lime will vary with limes from 2.5 to 3 times the volume of the lime (quicklime), and it is important that all the water required to reduce the lime to a proper consistency should be given to it before the temperature of the water first given becomes sensibly elevated.

Immediately upon the lime being provided with the requisite volume of water, it should be covered, in order to confine the heat, and it should not be stirred while slaking. When the paste is required for grouting or whitewashing, the water required should be given at once, and in larger volume than when the paste is required for mortar, and when slaked the mass should be transferred to tight casks to prevent the loss of water. When the character of the limes, as with those of hydraulic energy, will not readily reduce, their reduction, which is an indispensable condition, must be aided by mechanical means, as a mortar mill.

The process here given is termed drowning. When the lime is retained in a barrel, or like instrument, immersed in water, and then withdrawn before reduction occurs, it is termed immersion, and when it is reduced by being exposed to the atmosphere, and gradually absorbing moisture therefrom, it is termed air-slaked.

Bricks should be well wetted before use. Sea sand should not be used in the composition of mortar, as it contains salt and its grains are round, being worn by attrition, and consequently having less tenacity than sharp-edged grains.