RCD Corporation® #9 Mastic® Low To High Velocity Air Duct Sealant is a low VOC adhesive-sealant used for permanently sealing the fabricated joints and seams of sheet metal air ducts, UL listed rigid fiberglass air ducts, UL listed flexible air ducts and thermal insulation. RCD Corporation® #9 Mastic® is preferred by contractors for new fiberglass ductboard installations. It is ideal for repairing damaged and leaking air ducts and sealing conditioned spaces from air infiltration.

#9 Mastic® is more than an air duct sealant - due to its white color, ease of application and ability to adhere to all types of construction surfaces it is used as a termite monitoring system in buildings with crawl spaces. A 3" or wider stripe of #9 Mastic® around the top of  the perimeter of the crawl space creates an easily monitored zone for detecting termites crossing the barrier to the wooden structure. Easy application by brush, trowel, palm, spray or extrusion.

Adheres to many substrates, including but not limited to: