You would heat it in a gas flame, and use its pointed end for your soldering. Electric irons have made this a thing of the past, but the basic idea is still one with some merit.

Steel wire, screwdrivers, nails, and Alan wrenches are all potential tools for your emergency soldering. Just heat your wire or other steel tool over some open flame for 20-30 seconds and then ...

But overall, using the Cold Heat device was a success. The price of this new technology? Cold Heat’s soldering tool, with two tips, has a suggested retail price of $19.95. Batteries are extra.

Considering how cheaply you can pick up a cold heat yourself ($20 at ThinkGeek), it sounds like it really is worth adding to your tweakers aresenal. It’s Cool to Be Cold [PCMag] ...