Workwear zippers are specified for a different life from fashion zippers. A jacket may be worn for ten hours a day, loaded at the pockets, washed industrially at high temperature, and repaired rather than replaced. The zipper is often the first component to fail, and when it fails the whole garment leaves service because the wearer cannot close it.

This article describes a typical contract project: a heavy cotton or poly-cotton work jacket, a full front opening, two chest pockets, a detachable lining, and a laundry contract that washes garments at 60-75 degrees Celsius. The procurement team wants a zipper that survives the laundry cycle and can be replaced in the field.

1. Requirement: load cases and service life

Start with the load cases rather than the catalogue. For a work jacket they usually include:

  • Repeated opening: 20-30 cycles per day, five days a week, for two years, which is 10,000-15,000 cycles.
  • Cross-wise load: bending, reaching and squatting pull the front opening sideways, not just along the chain.
  • Pocket load: tools and a phone in the chest pockets put a peeling load on the placket above the pocket.
  • Laundry: 50-100 industrial washes, with detergent, temperature and mechanical action far beyond home care.
  • Repair: the zipper should be replaceable without discarding the garment.

Those requirements point to a larger chain, a robust bottom stop, a metal or heavy moulded slider, and a placket that can be opened for repair.

2. Selection: chain size, material and stops

A #8 or #10 nylon coil is common on heavy workwear because it is strong, light and tolerant of grit. A metal chain in #8 or #10 offers higher tensile strength and a more traditional look, but it is heavier and can corrode in a wet laundry environment if the finish is poor. Moulded plastic chains in large sizes are used on some utility jackets; they resist corrosion but are more sensitive to heat.

The bottom stop is the component that most often ends a workwear jacket's life. A simple crimp on a large coil can pull off under a repeated sideways load. Specify a reinforced bottom stop, or a design where the stop is enclosed in a bartacked tape fold. The top stop should be equally robust, because workers often pull the slider hard against it.

Slider choice should balance grip and snagging. A large puller is easier to use with gloves, but it catches on machinery and on the wearer's belt. A medium puller with a defined finger groove is a practical compromise. The lock body must hold under load; a semi-lock that releases too easily lets the jacket open while the wearer is working.

3. Key processes: attachment, placket and laundry compatibility

Heavy fabric demands a heavier needle and a longer stitch, but not so long that the seam opens under load. A common mistake is to use the same settings as the lighter lining, which produces a placket that is strong at the shell and weak at the lining attachment. Set the machine separately for each layer.

The placket should be designed for repair. A two-piece placket with a removable topstitch, or a flap that can be opened without cutting the shell, lets a repair station replace the zipper in 20 minutes. If the placket is sealed with a strong bar tack at both ends, specify a repair procedure that includes re-setting those tacks.

Laundry compatibility is a material question as much as a sewing question. Detergents and high temperature attack coatings, lacquers and some moulded sliders. Ask for wash testing in the actual laundry recipe, including drying, and check for slider stiffness, tape shrinkage and finish loss. If the garment is rented or leased, the laundry may be outside the brand's control, so the specification must be conservative.

4. Testing and acceptance

A practical protocol for this category:

  • Cycle test: 10,000 cycles, with a mid-point inspection at 5,000; record slider force and tooth condition.
  • Tensile: chain and slider assembly tested to a target agreed with the buyer, typically well above the load a wearer can generate.
  • Bottom stop pull-off: tested on the finished garment, not on a loose chain, because the tape fold contributes to strength.
  • Industrial wash: 50 cycles at the contract temperature, then repeat the cycle test on a shortened basis.
  • Abrasion: rub the placket against a representative tool belt or pack strap for 1,000 cycles.
  • Repair trial: replace one zipper on a finished garment and measure time and damage to the shell.

The repair trial is often the most revealing test. A zipper that passes every lab test but cannot be replaced economically will still take the garment out of service.

5. Common risks and how to close them

The first risk is a bottom stop that fails under sideways load, usually because the stop was specified for a lighter chain. The second is a slider that becomes stiff after industrial washing, often because detergent residue has dried inside the body. The third is tape shrinkage that shortens the front opening and makes the jacket feel tight across the chest after a few washes.

There are also programme risks. Workwear is often procured in large lots with a long service life, so a component change between lots is almost invisible at delivery and very visible two years later. Lock the specification, retain samples from each lot, and require written approval for any substitution. Finally, train the repair network on the correct replacement part. A repair station that fits a lighter slider to save time creates a recurring failure that looks like a design problem.