Black Swan's Pipe Joint Compound is a smooth, grit-free, gray colored pipe joint compound. It seals threaded joints tight and will not crack or crumble. Disassembly months or years later is easy. Contains no lead and is safe for all water systems. Black Swan's Pipe Joint Compound is recommended for use on all types of metal connections. Not recommended for use on plastic. Black Swan Pipe Joint Compound can be used on lines carrying air, water, steam, natural gas, ammonia, brine, dilute acids and alkalies. Not recommended for lines carrying oxygen.