Waterproofing a bike light with silicone grease

Here is the silicone grease, costs about £5 a tube,

I disassembled the light (and removed the gasket) and applied a very small amount – you need hardly any (if it gets on your hands its almost impossible to remove).

Complete, totally waterproof (hopefully)  I also applied a little to the battery terminals to prevent corrosion. Same process for torches.