What cause air entrainment in a dried coating?
There are many possible causes for air entrained in applied roof coating… One may be air that became entrained in the coating during manufacture, shipping or on-site mixing. Most roof coatings contain some components called defoamers that are designed to reduce the amount of air entrapped in the wet coating during manufacture. On-site mixing may actually whip air into the coating. Another source for air entrainment occurs when the coating is rolled onto a roof. If the coating is rolled “aggressively”, then air can also be whipped into the coating. A third source is when the coating is applied using an airless sprayer. If the draw side of the pump has a small leak, air can be sucked into the coating stream as it enters the pump. Since the coating is viscous and is under suction at this point, no coating will seep out of the plumbing connection.
