Touch 'n Foam Professional foam sealant is a high-performance, moisture curing, expanding polyurethane foam sealant. Foam sealant provides a permanent seal against air, moisture and insect infiltration while improving comfort and reducing energy usage. Use foam sealant to seal around plumbing, ventilation outlets, electrical junctions, between sill plates and concrete slabs or anywhere you need a fast, economical air-sealing moisture barrier.