Repairing Nicked Extension Cords

[Tonyg]

I use Liquid Tape Electrical. It is a rubber coating for use as electrical tape and insulation. This flexible coating exhibits excellent protection from acid, alkaline, and abrasion, as wells as sealing out moisture and salt permanently. It comes in a container with a built in brush in the lid. I believe it also comes in an aerosol, but I have not tried that.
It is very flexible and bonds really well, feels like rubber to the touch.