How things work ยท No. 10
How a zipper holds
A working model of a metal zipper, sliced through the middle so you can see inside the slider. Every tooth follows the channel the way a real one does.
The zipper
The slider
Slide slowly and watch one tooth. It only tilts while it is inside the slider. Then pull sideways on the part that is already closed.
What is simplified
- The whole zipper is sliced through the middle. On a real tooth the bump is a small dome and the hollow is a closed pocket, so you cannot see either from the front.
- Each row follows one fixed curve through the slider and beyond it. Real tape is cloth: it has a little slack inside the channel, and the open ends above the slider hang wherever the garment puts them.
- The teeth are drawn chunkier and the channel a little roomier than on a jacket zipper, so the bump and hollow are easy to see.
- This is a closed-end zipper, the kind on trousers and bags. A jacket zipper replaces the bottom stop with a pin and a box so the two sides can come fully apart.
In short
A zipper is two rows of identical metal teeth clamped to cloth tapes. Each tooth has a small bump on top and a matching hollow underneath, and the rows are offset so each tooth faces a gap in the other row. The slider is a Y-shaped channel. Going up, its walls tilt the teeth so each bump can swing into the hollow across from it, then the rows straighten and lock. Pulling on the cloth cannot part them, because a bump can only get out by tilting. Going down, a wedge forces the rows apart around a bend, where the teeth can tilt and let go. Stops at the ends keep the slider on.