The duct mastic is non-flammable, non-toxic, and dries completely within 30 minutes of application. Once ducts have been sealed, the problem of losing conditioned air

Is duct seal toxic?

Acute Toxicity Product Information . Inhalation Do not inhale. May be irritating to the eye. Skin Contact May be harmful in contact with skin.

Does mastic sealant smell?

mastic as far as I can tell doesn’t have a smell and is typically hard within a day or so. Most kinds are similar to that of caulk. In some cases in building returns and such I’ve used spray foam to seal the new return to the sheetrock for a good sturdy air tight seal.