ND ST-3® is a tough, resilient thread sealant for fasteners with straight or tapered threads. It is dry to the touch, seals instantly and forms a custom-fitting elastic gasket that prevents the passage of most fuels and chemicals, and helps keep joints tight, even under severe vibration. The material resists natural gas, butane, propane, motor fuels and chemical solvents. Various colors are used to identify particular characteristics of the parts to which it is applied.