The product we now call “duct” tape was originally manufactured by Johnson & Johnson’s Permacel division during WWII.
The military needed a waterproof tape that would keep moisture out of ammunition cases. For this reason, the original “duct” tape was only available in army green.
Because it was green and shed water (like a duck), WWII soldiers began calling it “duck” tape and, due to its waterproof nature, strength and built-in adhesive, they soon began using it for all sorts of repairs - even using it to close wounds in a emergencies!
So how did it come to be associated with duct repairs and become predominantly silver?
The returning soldiers brought with them the green “duck” tape as well as a housing boom. This prompted savvy manufacturers to begin selling the miracle adhesive as a way of connecting heating and cooling ducts in many of the homes being built. To that end, they changed the color to silver and it quickly became known as “duct” tape.