Higher air temperatures increase the temperature of sand, cement, lime, water, masonry units, and equipment, all of which result in hot mortar. Mortar at high temperature: is less workable; contains less air; sets faster; loses water faster through evaporation; and loses more water from absorption by masonry units. Of all of these, the major problem is water loss. How do you prevent this water loss in hot weather? Here are some suggestions. MATERIALS Keep materials as cool as possible. Cover or shade the sand, cements, and masonry units. To prevent brick from absorbing water, wet the brick before laying it, but only if its initial rate of absorption (IRA) is greater than 30 grams per minute per 30 square inches. EQUIPMENT Locate the mortar mixer and materials in the shade. Flush the mortar boards with water before, after, and between loadings. CONSTRUCTION Keep the mortar moist; retemper if necessary. Do not spread mortar beds more than 4 feet ahead of the masonry. Apply a light fog spray directly to the walls during the first 24 hours.