Resistant to all refrigerants, oils, water, and most chemicals, these joint-sealing compounds help to form a flexible, fluid-tight seal. They can be used on all metal or plastic surfaces, and are also recommended for joining dissimilar metals and materials. They help to prevent loosening of nuts, bolts, plugs, and fittings. They also help to successfully seal refrigerants in HVAC applications, including CFC's, HFC's HCFC's, and PFC's.