Q: Which zipper system fits a trench coat?
A trench coat takes a size 5 two-way metal or vislon zipper, open-end, with a long pull that clears the storm flap. The two-way slider is not optional on a coat of this length: the wearer needs to open the hem when sitting or driving, and a single slider forces the whole front open instead. Set the bottom box at the hem, keep the chain straight through the placket, and allow the flap to overlap the slider by at least 15 mm so rain does not reach the teeth.
- Size 5 metal or vislon, open-end, two-way.
- Long pull that clears the storm flap.
- Bottom box at the hem; flap overlap of 15 mm or more.
The common pitfall is a single-slider zip, which fights the wearer the moment they sit down and eventually bends the chain. The second is a short pull buried under the flap, so the coat cannot be closed without fumbling. Because the flap hides the tape, check the pull length with the coat on a dummy, not on the flat pattern.