Here’s an ad for a hair care product from the April 16 1930 edition of the Toronto Daily Star:
Kay English has an Internet Movie Database entry; she was born in 1911, so she would have been 18 at the time of this ad. She had parts in movies, mostly uncredited, between 1928 and 1958. Her biography lists her as being in the cast of Show Girl (1929), but I couldn’t find a reference to her in Show Boat.
The American History website from the Smithsonian Museum has this entry on Danderine. It was sold from the late 1890s to 1945, at which point it gave way for a while to Double Danderine.
I also found this page on the history of Danderine.