Nu-Calgon 4371-38 Thermo-Trap Putty

Thermo-Trap Putty is a reusable putty material that is referred to as a heat sink. Thermo-Trap keeps components protected and cooler much better than a traditional wet rag. When applied to the metal working surface, Thermo-Trap soaks up heat and reduces heat transfer to protect sensitive components. Apply to copper, steel, or other pipe surfaces before welding, brazing, or soldering to protect nearby sensitive controls or components. Thermo-Trap Putty also protects adjacent surface areas from over-heating or damage prior to welding, brazing or soldering.

This product must be used in accordance to the following directions by HVACR professionals only.
Before you solder, braze or weld, wrap a collar of Thermo-Trap Putty around the metal work surface between the area being heated and the material to be protected. The amount required will vary depending on the thickness and heat-conducting properties of the metal being worked on, the temperature of the heating tool, and the length of time heat is applied. Your own experience will be the best guide in deciding how much to use. Remember, too much Thermo-Trap can’t hurt. Too little could. Be sure Thermo-Trap contacts the metal surface closely all around and there are no pockets or voids where heat might transfer through. After the job is done, remove the Thermo-Trap Putty and place it back in the container.