Waterproofing a solder connection

Has anyone tried covering a solder connection with 5 minute epoxy then using heat shrink over it before it sets?
Water can travel between wire strands or between wires and the insulation. Glue lined heatshrink would let water pass over the solder connection from under the insulation of one wire and continue into the next wire. The glue is unlikely to form a perfect seal around the solder connection.
Epoxy should block that path and shrinking the cover should squeeze it into and around the wire and solder. The heat would help the epoxy set but not instantly in my experience.

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This sounds like a really nice idea :+1: Just wonder if there is a risk that the epoxy might not prove a durable water seal? Its quite brittle so may fracture if constantly flexed. Marine grade heat shrink would keep the connection more stable but wonder if this would eventually fail when used underwater?

A ex-Navy diver friend of mine told me that he used to make splices good to 1,000 feet deep using just heat shrink and silicone. He’d slide the heat shrink over the soldered joint, fill the whole area with liquid silicone goop, then start shrinking the heat shrink from the center out, causing much of the silicone to get squeezed out the ends. You’d have to be careful to not have any air bubbles in the silicone and I would think that this wouldn’t last more than a couple of years, but it makes sense to me and seems to follow the same principle as oil-filled pressure-tolerant electronics. No warranty expressed or implied!


That’s a great method - thanks!