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Most zip faults are caused by a worn slider rather than the chain itself. If the zip splits open behind the slider, it is usually enough to squeeze the slider slightly or replace it with a new one of the same size and type. A zip repair that requires replacing the whole zip is needed when teeth are missing, the coil is torn or the tape is ripped.
Zip repair: diagnosis first
Before unpicking anything, determine exactly what is not working. This decides whether the repair takes five minutes or the whole zip has to be replaced.
| Symptom | Likely cause | Solution |
|---|---|---|
| The zip splits open behind the slider | Spread (worn) slider | Squeeze or replace the slider |
| The slider sticks | Caught fabric, thread or dirt | Cleaning, lubrication |
| The slider comes off the chain | Missing top or bottom stop | New stop |
| Teeth are missing | Mechanical damage | Replace the zip |
| The open-end zip will not engage | Damaged box or pin | Usually replace the zip |
| Broken puller | Wear | New slider or puller |
The zip splits open: squeezing the slider
Over time the two plates of the slider spread apart and it no longer presses the teeth together enough. A temporary solution is to squeeze it lightly with pliers:
- Move the slider down to the bottom stop.
- With pliers, lightly squeeze the back of the slider (the end from which the closed zip emerges) – first on one side, then on the other.
- Test after each squeeze. Too much force can crack the slider, especially if it is zinc alloy.
This often helps with metal zips. With plastic sliders it is risky, and with badly worn ones only temporary.
Replacing the slider
Replacing the slider is the most common professional repair. The new slider must match on three parameters: chain type (coil, metal or moulded tooth), size (No. 3, No. 5, No. 8…) and type (auto-lock or not). The size is often stamped on the back of the old slider.
Steps for a closed-end zip
- Remove the top stops on one or both sides with pliers.
- Take the old slider off the top.
- Insert both tapes into the new slider at the same time and at the same height, then run it down and back up to check that it engages.
- Fit new top stops or sew a machine bartack in their place.
For an open-end zip
On open-end zips the slider can often be replaced from the top in the same way. If the box or pin is damaged, the repair is rarely lasting – it is better to replace the whole zip.
Stuck slider
- If fabric is caught, pull it gently backwards, not forwards.
- Clean the chain with a brush – sand and salt get stuck especially in plastic zips.
- Lubricate with graphite (pencil), wax or paraffin. Avoid greasy oils on light fabric.
Missing stop
Without a top stop the slider comes off the chain; without a bottom stop on a closed-end zip the two halves separate. Metal stops are fitted with pliers, and on nylon coil zips you can sew a few tight hand stitches or a machine bartack in place of the stop.
When it is better to replace the whole zip
- teeth are missing or broken;
- the coil is torn or melted;
- the tape is torn or worn through;
- the mechanism of the open-end zip is damaged;
- the zip has already been repaired once and the problem keeps coming back.
Replacing a zip on a jacket or bag requires unpicking seams and topstitching, so for a repair the new zip should have the same length, size and tape width so that the seam falls in the old place.
Zip repair by type
Metal zip
Metal zips rarely lose teeth, but the slider wears out and the stops fall off. On jeans the teeth often oxidise and the slider sticks – cleaning and dry lubrication help. If one tooth is bent, it can sometimes be carefully straightened with pliers.
Nylon coil zip
The coil can "open" or become distorted, especially after ironing with a hot iron. If a small section at the bottom end is deformed, the zip can sometimes be shortened above the damage. A coil torn in the middle cannot be repaired.
Moulded zip
On plastic zips the weak point is the individual tooth – if it breaks off, the slider will split the chain at that spot. A missing tooth in the middle of the zip means replacement. On winter jackets, damage to the box of the open-end zip is also common.
How to reduce complaints in production
For brands and factories, zip repair is a cost that can be prevented when choosing the product:
- choose a size that matches the load – too small a size on a jacket is the most common cause of a splitting zip;
- on trousers, use auto-lock sliders only;
- for outdoor products, prefer moulded plastic zips, which do not corrode;
- test a sample under real conditions – washing, folding, load.
You will find spare zips and sliders of various types in the zips category, including metal zips for jeans and leather.
Polkom – zips and sliders for ateliers and manufacturers
Polkom is a Bulgarian manufacturer of accessories for fashion, furniture, footwear and bags with over 30 years of experience. We deliver zips and sliders to repair ateliers, garment factories and brands across Europe. Send an inquiry with the type, size and quantity – we will suggest a suitable option and a sample.
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