The new professional-grade caulk, plumbers firestop sealantâ„¢, expands up to 10 times to block flame propagation, the company says. With a fire rating of up to three hours, this highly flexible, low-odor sealant can be used for general plumbing, HVAC, bath and dryer vents, pipes, ductwork, etc. According to the manufacturer, the sealant is water resistant once it cures, and it will not sag, separate, or shrink when dry. The company says the sealant provides an excellent smoke seal, reduces noise transmission, and is paintable.

Hercules Chemical Co. Inc., 111 South St., Passaic, NJ 07055-9100; 973-778-5000;;

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