Demolition operations, acts of sabotage, controlled destruction of material. Just three examples of fundamental missions that depend on something as simple as a well-connected cable. But tin and traditional soldering irons are an impossible luxury at the front, and when the goal is to create solid joints in the mud, under the rain, trapped in the snow, or while avoiding enemy fire, a different kind of tool is needed: copper sleeves that ignite like matches.
Hollywood used the same scene dozens of times: someone tries to detonate an explosive charge, pulls the lever or pushes the button… and nothing happens because of a bad connection. It might even be funny when we see it on screen, but a failure like that could cost lives in the real world, especially in wartime. When it comes to joining cables safely and consistently, we have the privilege of a soldering iron and a roll of tin, but that was not the case for soldiers and agents.
The Solder Sleeve Solution
Thanks to a recent video published by the channel ElementalMaker, we now know exactly what they used to solder cables. At first glance it looks like a matchbox, and if we are honest, the devices could be seen as distant cousins. They are sleeves of "automatic solder", made up of small copper tubes that contain the right combination of tin and flux, and a substance on the outside that ignites without a flame when rubbed against a rough surface.
How It Works
Fortunately, ElementalMaker's sample includes the original instructions and the manufacturing date, 1964. The first step is to strip the insulation "at least a quarter inch more than half the length of the sleeve". Then the wires are cleaned with a knife (very important), and inserted into the sleeve as far as possible. That is when the sleeve is rubbed to ignite it, and once the tin melts, the user pushes the wires the rest of the way, intertwining the copper ends inside the sleeve.
The last three steps are to hold the joint firmly until it cools, remove the burned material, and isolate. At the end, the instructions remind the user that "cleanliness is essential", and recommend not touching the cables after they have been exposed. How old is this tool? The patent mentioned by ElementalMaker, US934711A, dates back to 1908, and lists Frank Spencer Chapman as its inventor. A design 112 years old, working perfectly in 2020.
