A zip
The zip still works. The slider doesn't. Here's how to tell, and what to do.
What to check first
- Teeth — inspect along the full length for missing or bent teeth before assuming slider wear
- Slider channel — the gap that widens with use; visible if you look at the slider end-on
- Tooth alignment — a zip that gapes behind a moving slider almost always has a worn slider, not broken teeth
One moving part
When a zip fails, the teeth get the blame. Look more carefully and nine times in ten the teeth are fine — clean, unbroken, properly moulded. The slider has simply worn loose. Its internal channel, which bends the teeth together on the closing pass, has widened fractionally with use. The teeth meet, then spring apart again an inch behind the slider. That is the signature of a worn slider, not a broken zip.
Before doing anything else, hold the zip closed at the base and run the slider up slowly. If a clean, locked closure follows it all the way up, the teeth are sound. If the closed section falls open again in the slider's wake, the slider is the problem.
The fix needs nothing beyond a pair of flat-nosed pliers. Lay the slider on a hard surface and find the two flanges — the flat lips that run either side of the tooth channel. They need to be squeezed very slightly closer together. Work both sides evenly, a tiny amount at a time: too much and the slider jams and won't move at all. After each small squeeze, run the slider along a short section of zip. You are looking for the point where it closes and stays closed — smooth to move, leaves nothing gaping. It takes a few attempts. It is worth the patience.
If a tooth is actually missing or bent sideways, that is a harder problem. A bent tooth can sometimes be coaxed back with a needle or a pin — gentle lateral pressure, not force. A missing tooth means the zip needs replacing, which is a job for a zip foot on a sewing machine and fifteen minutes of calm work, or a tailor.
Most zips, though, don't need replacing. They need thirty seconds with pliers and the attention to try the thing before throwing it away.
Where we stop
No mains electricity, gas, water mains, boilers, flues, roofs, ladders past single storey, structural work or anything requiring a qualified person. If a job could hurt somebody, it is not in this register.