Explainer No. 6
Two rows of teeth that lock together, and a slider that brings them in at an angle. Every tooth has a bump and a notch; the trick is getting each bump into the right notch.
The slider is see-through here, so you can watch the teeth lock as they leave it.
Point at a part to find it in the drawing. Real zippers vary; this one has metal teeth.
Strips of woven fabric sewn into the garment. Each carries one row of teeth, clamped onto a corded edge.
Each has a bump on its top and a notch in its underside. Locked, every bump sits in the notch of the tooth above it.
The part you move. Inside is a Y-shaped channel that steers the two rows together, or apart.
A V-shaped post between the two ways in (also called the separator). Pull the slider down and it forces the rows apart.
What you hold. On many zippers it also works a little lock.
Two at the top keep the slider from running off; one at the bottom joins the tapes.
Elias Howe patented a clothing fastener in 1851 but never seriously tried to sell it. Whitcomb Judson's "clasp locker" of 1893 was meant for shoes. Gideon Sundback, a Swedish engineer in Meadville, Pennsylvania, patented his "separable fastener" in 1913 and an improved one in 1917, and in 1923 built a machine to make them.
In the 1920s the B.F. Goodrich company sold rubber boots that fastened this way as Zipper Boots, and helped make the name popular.
This one has separate metal teeth set along each tape, the kind suited to thick fabric. Molded zippers have teeth of injected plastic. Coil zippers have no separate teeth at all: a plastic spiral along each tape forms them. An invisible zipper hides its coil on the inside, so the seam looks finished.
A zipper that has to come fully apart, like a jacket's, has no bottom stop. Instead, a pin on one tape slides into a box on the other before you zip. Two-way zippers can be opened from either end.
On many zippers the pull tab works a lock. Lower it and pins on it push down into the teeth, so the slider stays put. YKK calls this a pin lock.
If the teeth come apart again just below the slider, the slider is usually bent: its jaws have spread, so it no longer squeezes the rows together. Repair guides suggest pressing it back with pliers, a little at a time and evenly on both sides; overdo it and the zipper gets hard to zip. A missing tooth usually means a new zipper.
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