Two-Way and Separating Zippers on Jackets

How a separating (two-part) zipper works

A separating zipper is also called an open-ended zipper, because the two halves come apart completely at the bottom. What holds them together is a small mechanism at the base: an insertion pin at one end and an insertion box (retainer box) at the other. When you seat the pin all the way into the box and pull the slider up, the slider grabs both rows of teeth and closes the jacket. On an ordinary closed-end zipper – in trousers or a skirt – the ends stay joined at all times; on a jacket they have to be re-joined every time. That is exactly why a jacket zip has more places that can fail, and why the diagnosis matters before you do anything.

Separating or two-way – one slider or two?

Before troubleshooting, check which type you have. They look alike but behave differently:

• Separating (open-ended): one slider, splits only at the bottom. Most common on jackets and cardigans.
• Two-way: two sliders on the same set of teeth, so you can also open the zip from the bottom. Common on long coats, parkas and boiler suits, so you can sit and move more easily.
• The two-way version has twice as many sliders that can wear – and the bottom slider is often the culprit when a long jacket suddenly 'gapes' at the hem.

When the pin won't go into the box

The most common cry for help: the pin won't seat, or it jumps back out the moment you pull. Try this calmly – don't force it, or you'll bend the pin or tear the fabric:

1. Pull the slider all the way down to the base of the teeth first, so the opening in the slider is ready.
2. Straighten the pin and the teeth with your fingers if they are bent – a bent pin never meets the box correctly.
3. Feed the pin straight down and fully into the box, not just halfway. Hold the bottom of the jacket taut with your other hand.
4. Pull the slider up smoothly while keeping the pin seated. Never yank – if it jams, go back down and start again.
5. If it still won't grip, feel for a missing or bent tooth just above the box. If so, it isn't the pin but the teeth that are the problem.

The zipper splits open behind the slider

Does the zip close as you pull it up, but spring open again just behind the slider as you walk? That is almost always a worn-out slider, not the teeth. Inside the slider are two channels that press the rows of teeth together; after thousands of pulls the channels widen and lose their grip. The teeth can look perfectly intact – it is the slider that no longer squeezes them shut. The good news: if the teeth are whole and straight, often just the slider can be replaced without changing the whole zip. But if teeth are worn, missing or deformed, a new slider won't help – then the whole zip must be replaced.

When the whole zip must be replaced

Some damage can't be fixed with a knack: a cracked insertion box, missing or broken teeth, a snapped-off pin, or a row of teeth that has come away from the tape. Then the whole zipper has to come out and a new one go in. On a jacket this is a bigger job than on trousers, for several reasons:

• The new zip has to match in length, tooth type (coil, plastic or metal), gauge and colour – and be a separating type, or the jacket won't open.
• The zip is often sewn in under a storm flap, a lining edge or a placket, which must be opened and closed again neatly.
• On technical jackets and down jackets the seam sits close to the membrane or down chambers, so the swap must be done carefully to avoid damaging the rest.

Send the jacket to us

If you are unsure whether it is the slider, the box or the whole zip – or you simply want it done right – you can send the jacket to us. We assess the zipper and replace what needs replacing, matched to tooth type, length and garment, and sew the new zip in the way it originally sat. If the jacket needs another repair at the same time, we handle it in the same round. You order online from anywhere in Norway, and you see the price before you order.

Frequently asked questions