3M™ Scotch-Weld™ Void Filling and Edge Sealing Compound EC-3524 B/A is a two-part flame retardant epoxy and can be used as a fairing compound for aerodynamic flushness, for reinforcing honeycombs, bonding inserts, and sealing and providing impact resistance to honeycomb panel edges.3M Scotch-Weld Void Filling and Edge Sealing Compound EC-3524 B/A can be used for void filling, edge sealing and as an abradable compound in aircraft engines. It is sandable within three hours of mixing and cures to a strong, low-density material within 48 hours at 24C / 75F. The compound has thixotropic properties for ease of application. To ensure complete and uniform mixing, the base is blue and the accelerator is white. It meets the flammability requirements of F.A.R. 25.853 (a) and (b).