Coating Application

The crystalline waterproofing coating materials are mixed with water at a ratio of five parts powder to two parts water by volume for brush application, and five parts powder to three parts water by volume for spray application. The coverage rate is 1.25 to 1.5 pounds per square yard per coat. At this rate, a 60-pound pail of material will cover 360 to430 square feet, and a 50-pound bag will cover 300 to360 square feet of surface area.

Coatings can be applied by brush, hopper gun or specialized spray equipment. When using a standard six-inch masonry brush, one person can mix and apply approximately 80 to100 square feet per hour per coat. A hopper gun or texture gun uses a two-person crew with one person mixing material and the second person spraying. The gun uses a three-eighths inch nozzle and operates at roughly 25 psi. A two-person crew can apply the coating at a rate of 400 to500 square feet per hour per coat.

Specialized spray equipment is operated with a three-person crew. At application rates of 1200 to1500 square feet per hour per coat, it is necessary to have all materials pre-measured in order to keep up with the spray equipment capacity. When using this type of equipment, the best procedure is to pre-measure the powder into at least five or six large buckets (five gallon pails) and pre-measure the water. This is done on the basis of five parts powder to three parts water by volume.

On vertical surfaces, the standard application procedure is to start at the top of the wall and work down. When using spray equipment, the first coat of material can be back-brushed using a 20-inch wide janitors broom with a soft bristle or a finisher's broom. This helps ensure an even coverage rate and minimizes any run down of the coating.

When a second coat is specified, it needs to be applied no later than 48 hours after the first coat. Under normal conditions, the crystalline waterproofing coating will begin to set up in two to three hours and application of the second coat can be done at this time. If the first coat has dried out, it should be lightly moistened with water prior to the second coat being applied. Failure to do so may result in lack of bond between the two coats.

When applying the coating materials to a concrete structure, it is better to break the job up into manageable segments rather than try to complete large areas at one time. This becomes even more critical when the weather is hot or windy.