Dating talon zippers
UPDATE: Please note that the zipper I am referring to in this article is the nylon coil zipper, as shown on the right in this photo.
Earlier plastic zippers were available and were most often used as a decorative element.
Sundback's hookless fastener depended on the action of a series of closely spaced elements, technically called "scoops," whose precise spacing and ingenious shape are key to the fastener's success.
Each scoop has a dimple on one side and a protruding nib on the other.
But many people believe if a garment has a nylon zipper, it probably dates to the mid-to-late 60s at the earliest. Today I came across this ad for the "New" Talon Zephyr zipper in a magazine from October of 1960.
While it is true that nylon coil zippers were not immediately popular, you will find early ones from time to time, especially in designer garments.
The slider's function is simply to bring the two rows of scoops together (or to separate them) in a continuous, serial action.