Here's why the name "slide fastener" was used for what is now known as "zipper":
Quote:
In 1923, (BF) Goodrich adopted and trademarked the name "Zipper Boot" due to the more dramatic sense the word "zip" created. Meanwhile, the Meadville company stepped up production and choose the name "Talon" for its product (and in 1937 the company), believing the name epitomized their product's "positive qualities" (Petroski). Goodrich purchased millions of the Hookless Company's Talons, who would go on to produce 20 million in a single year by 1930. Though originally a trademark of Goodrich, zipper came into common usage as the generic, relegating names like slide fastener and Talon to obscurity.
And do keep in mind that even though the above advertising cover was postmarked 1940, it was apparently old then, as there is the block-out of the business address in San Francisco, reprinted with the Los Angeles address above it. Probably a cost effective means to re-use a ton of advertising envelopes already in inventory.