What's the source of the expression/verb "cotton to" (eg "I don't cotton to that idea")

[bob_2]

Michael Quinnon from World Wide Worlds has the authoritative answer. Cotton on
It’s complicated, but I’ll try to unravel it for you…

By the middle of the sixteenth century the verb sense of cotton had become a figurative expression meaning to prosper or succeed. A writer in 1822 tried to explain it: “a metaphor, probably, from the finishing of cloth, which when it cottons, or rises to a regular nap, is nearly or quite complete.”

By about 1600, to cotton together or cotton with a person meant you got on well together. It has plausibly been suggested it came from the use of mixtures of cotton and other fibres in clothing. A little later, cotton up meant to strike up a friendship. In the early 1800s, to cotton to somebody implied that you were drawn or attached to that person. It may be that the idea here is how well a thread of cotton sticks to the surface of cloth. Cotton to was taken to Australia and became common there:

“My word! Dick,” Jim says, “it’s a murder he and Aileen didn’t cotton to one another in the old days. She’d have been just the girl to have fancied all this sort of swell racket, with a silk gown and dressed up a bit.”
Robbery Under Arms, by Rolf Boldrewood, 1888.