Detective magazines, comic books and early fetish magazines
Gold Seal Detective magazine cover, June 1936
image sourced here. [Jun 2005]
In the early 20th century ...
In the early 20th century, "Detective magazines" covertly provided a way of publishing bondage imagery. Comic books often featured characters being tied up and tying others up, particularly in "damsel in distress" plots.
There were also a very limited number of specialist fetish magazines which featured images of bondage, such as the famous Bizarre magazine published from 1946 to 1959 by the pioneering fetish photographer John Willie, and ENEG's Exotique magazine, published 1956 - 1959. These disappeared with a crackdown on pornography in the late 1950s. --http://en.wikipedia.org/wiki/Bondage_magazine#Detective_magazines.2C_comic_books_and_early_fetish_magazines [Jun 2005]