One of my own songs has a reference to black hair texture. It's a story about a romance between a white girl in Virginia and a slave; full lyrics at my website - direct to this song.

The lines in question are:

"This Irish girl was not annoyed by kinks in Johnny's hair
Nor paid she mind the coloured blood to which he was an heir..."

And the source I used for it said this:

"It is very certain, that this Irish girl was not annoyed by the kinks in John's hair. Nor was she overly fastidious about the small percentage of colored blood visible in John's complexion."

Source: The Underground Railroad, William Still, 1879 (you can read the original story on the link through my website).

Marion