Boeing has qualified a new-generation, high-solids, low-volatile organic compound (VOC) exterior epoxy aerospace primer from PPG Aerospace - PRC-DeSoto. The primer, Desoprime HS CA7700, reportedly exhibits superior adhesion, flexibility and rain-erosion resistance, according to PPG coatings officials.

The epoxy primer is qualified to Boeing specification BMS 10-72 Type VIII and will soon be on all new Boeing aircraft painted with Desothane HS topcoat, said Alan Schoeder, PPG Aerospace commercial coatings market manager.

“Desoprime HS CA7700 primer has superior wetting on marginal surfaces to provide long-term adhesion even to rivets,” Schoeder said. “This primer addresses the problem with what is commonly called ‘rivet rash.’ It won’t shrink from rivets and maintains adhesion over time to provide protection from corrosion, maintaining the smooth topcoat appearance.”

Already qualified by Bombardier Aerospace and Embraer, the primers have passed the whirling arm test for rain-erosion resistance and filiform salt fog test for corrosion resistance, Schoeder said. There was no loss of adhesion or cracking at 40 inch-pounds with impact testing, he added.

“This primer applies smoothly to metal and composite surfaces with superior adhesion to give the topcoat better distinctness of image,” Schoeder said. For aircraft maintenance operations, the primer reportedly is easier to spray and dries within two hours, much faster than other high-solids primers.

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