RectorSeal® Tru-Blu Pipe Thread Sealant with Ptfe Is A Fast-Dry, Flexible Set Thread Sealant Designed For High Vibration Environments Such As Refrigeration and Industrial Applications. PTFE Has Been Added To Enhance Thread Lubrication During Assembly and Break Out. Recommended For Use On Threaded Galvanized Steel, Iron, Brass, Copper, Aluminum, Stainless Steel, Polyethylene, Fiberglass Reinforced, PVC. Great For Use As A Positive Lock and Seal On Threaded Fasteners. Certified To NSF/Ansi 61-G.