3M Aerospace Sealant AC-251 (Black, Class B)

A two-part, quick-curing, solvent-free polysulfide sealant formulated for sealing aircraft windshields, canopies and windows and for exterior mold-line applications. Supplied as a black, non-sag thixotropic paste that holds its shape on vertical and overhead surfaces, does not craze, and gives excellent adhesion plus UV/weather and fuel resistance on acrylic, glass and polycarbonate transparencies.

Angad Aviation supplies this 3M product with full traceability and documentation — request a quote for current pricing, pack sizes and lead time.

• Brand: 3M
• Part No.: AC-251
• Chemistry: two-part, manganese dioxide-cured polysulfide, solvent-free
• Color: black
• Form: non-sag thixotropic paste; injection gun or spatula
• Application life classes: B-1/2, B-1, B-2 (~0.5 / 1 / 2 h)
• Cure: ~4 h / 7 h / 9 h respectively
• Substrates: acrylic, glass, polycarbonate transparencies (does not craze)
• Applications: windshield, canopy and window sealing; exterior mold line
• Compliance: Boeing MAT-587 qualified (Class B-1/2, B-2) per distributor listing