I’m finding it difficult to control microfoam and pinholes in my airless spray applied topcoats. What would you suggest?
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Lead Research Chemist
Microfoam is caused by small air bubbles that are caught in the paint film by the spray process and rise too slowly in the drying film, so they remain trapped at or beneath the surface. Pinholes are often caused when these small bubbles break free at the surface, and the film is too viscous to flow back and fill the hole left behind. Pinholes can also appear when coatings are baked; bubbles, initially trapped below the surface, rise as the coating flows under the heat and before it gains viscosity through cross-linking.
Deaerators are needed to bring these bubbles to the surface quickly so that the air can be released before the film sets. Molecular defoamers, such as Surfynol® DF110C defoamer or Surfynol® AD01 defoamer are effective deaerators for many spray applied coatings. These products can also be used in combination with other defoamers, such as Surfy¯nol DF58 defoamer or Surfynol DF70 defoamer, if stronger defoaming is required.