[zarzavat]

Fascinatingly this folk etymology is incorrect. According to Wikipedia[0], the “duck” refers to cotton duck[1], a strong fabric that can be made waterproof, from which the original duck tape was made.

“Duct tape” (with a T) is in fact the retronym and was coined when duck tape started to be used for ducting.

All of this doesn’t explain how Duck-brand tape managed to get a trademark on an existing generic term.

[0] https://en.wikipedia.org/wiki/Duct_tape#History

[1] https://en.wikipedia.org/wiki/Cotton_duck

[jasonhansel]

To clarify: I'm not claiming that the phrase "duck tape" in its original sense was derived from the branded product "Duck Tape"; as you point out, the phrase "duck tape" came first, and was derived from cotton duck.

However, if you use the phrase "duck tape" not in its original sense, but as (effectively) a new word--as a genericization of "Duck Tape"--then you would (IMHO) be quite correct to call duct tape "duck tape."

I guess this depends on whether you think that this use of "duck tape" is actually a new sense of the phrase, or just a continued misusage of the preexisting sense.

I would argue for the former, since IIRC the phrase "duck tape" actually fell out of popular usage for a while before the time when the Duck brand emerged.

This suggests that the phrase "duck tape" was effectively resurrected with a new meaning--that of a genericized trademark derived from the "Duck Tape" brand.

Google Ngram Viewer seems to partially back this up--note that "duck tape" declined in popularity from 1943 to 1963, slightly reemerged around when the Duck Tape brand got its name in 1975, but only really took off between 1987 and 2007: https://books.google.com/ngrams/graph?content=duck+tape&year...

I can't explain why usage increased slightly between 1963 and 1975, though. Hmm...

[RScholar]

...1987, of course that's when interest would've spiked. IIRC, that's the year MacGyver debuted on TV.