A zipper described in a technical pack as "5# nylon, black, 65cm" tells a manufacturer something — not enough. That specification leaves the zipper type, slider configuration, colorfastness standard, regulatory compliance requirements, and pull tab design all unspecified. Each of those gaps is a decision the factory makes without input from the brand, and those decisions often produce the wrong result. Writing a complete zipper specification takes ten minutes and prevents weeks of clarification, resampling, and rework.
The Basic Construction Parameters
These fields belong in every zipper specification, for every application, without exception.
Zipper Type
Separating (open-end) or non-separating (closed-end)? One-way or two-way? If the garment or product opens fully and the two sides detach completely, you need a separating zipper. If the closure is a pocket, bag opening, trouser fly, or cushion seam, you need a closed-end. These are not interchangeable — ordering the wrong type requires a complete redo.
Tooth Material and Size
Nylon coil, plastic (resin/vislon), or metal? Specify the alloy for metal: brass, aluminium, zinc alloy. Size number: 3#, 4#, 5#, 7#, 8#, 10#? Larger numbers mean a wider, heavier, stronger chain. For a dress, 3# is standard. For a padded jacket front, 5#. For a structured bag or luggage piece, 7–10# depending on load requirements. If you're unsure which size is appropriate for your application, this is the first question to ask the supplier — it is easier to resolve in specification than after samples arrive.
Finished Length
Not tape length — finished zipper length, measured correctly for the zipper type (bottom of box to top stop for separating; bottom stop to top stop for closed-end). State the measurement method explicitly if there is any possibility of ambiguity. Include a tolerance: ±2mm is standard for most applications.
Construction Variants
Does this specification require anything beyond standard construction? Waterproof tape treatment, FR tape, anti-static treatment, anti-arching tape, chain format without stops?
Colour Specification
This is where most specification errors occur. The colour parameters for a zipper involve three independently specified elements.
Tape colour: Reference a Pantone number or attach a physical sample from the garment fabric you need it to match. State the light source under which the match must be evaluated. D65 (Artificial Daylight) is the international standard for textile colour matching. TL84 is appropriate if your end market is European retail, where a different fluorescent illuminant is standard in stores. Without a specified light source, an approval is meaningless — the same sample can look different under different lighting, and two observers will use different conditions.
Teeth colour: Specify separately from tape colour. On nylon coil, the tape and coil are dyed independently and may come from different dye batches. On plastic, teeth colour is set in the moulding process. On metal, teeth finish is a plating — specify: natural brass, silver nickel, antique brass, matte black, gold, gunmetal.
Slider finish: For metal zippers and for metal sliders on nylon or plastic chains, the slider plating finish is a separate specification from teeth finish. It must be specified to match the hardware language of the overall product.
Performance Requirements
Include these fields in your standard spec template, with N/A where not applicable. Omitting them when they are relevant is where compliance problems start.
Colorfastness: For garments with wash requirements, state the minimum colorfastness to washing grade required (typically grade 4 on ISO 105-C06) and whether crocking resistance (colour transfer to rubbing) is specified. This is particularly important when pairing dark or vivid zipper tape with pale fabrics.
Chemical compliance: State applicable requirements explicitly: AZO-free tape dyeing (required for EU market goods in skin contact), nickel-free metal components or REACH nickel release limit compliance, SVHC-free declaration, phthalate-free for plastic components. State whether a test report or a declaration of conformity is required as documentation. For children's clothing, these are non-negotiable line items.
Needle detection: If your production line includes needle detection, or if your buyer requires it, state the sensitivity level and confirm with the supplier that the specification is compatible.
Slider and Pull Tab Specification
Slider type: Auto-lock (slider won't move unless the pull tab is engaged — appropriate for outerwear and bags), non-lock (slider holds by friction only — appropriate for trouser flies), semi-auto (lock engages only at the fully closed position).
Pull tab: Standard (supplier's standard for the size and type specified) or custom (attach the drawing or reference the approved sample). For children's clothing, include the required pull-off force as a minimum: typically 70–90 N depending on the applicable buyer testing protocol.
Pull tab finish: If metal, specify the plating finish. If cord, specify material and colour.
The Sample Approval Process
A specification without a sample approval step is incomplete. Include in your tech pack: "Counter-sample required before production confirmation. Colour evaluation against D65. Pull-off force to be reported on sample submission documentation."
When reviewing initial samples, check: colour match under the specified light source, slider operation on your specific fabric (not on a test card), colorfastness (spot-wash test at the specified temperature), pull-off force if applicable, and dimensional conformity to the stated finished length.
For the quality criteria to apply when reviewing samples — construction finish, teeth consistency, slider smoothness — the guide to identifying high-quality zippers covers these in detail. For the wholesale ordering process once the specification is confirmed, see the wholesale zipper purchasing guide.
What Goes Wrong: Two Sample Rounds Lost to a Vague Spec
A fashion brand was developing a structured utility jacket. The tech pack specified: "#5 zipper, black, YKK or equivalent." Nothing else.
The factory sourced a #5 metal teeth zipper — black anodised aluminium teeth with a dark slider. Visually clean, mechanically correct. It was their default interpretation of "#5 black."
The designer had specified nylon coil. Not metal. The visual difference is significant: metal teeth have a structured, high-contrast look; nylon coil at the same size is almost invisible — a subtle, sleek closure. The garment's design intent required the coil version.
First sample: rejected. Supplier was briefed verbally that nylon coil was required. Second sample arrived with a nylon coil zipper — but the slider was a standard fashion slider with a flat pull. The designer wanted a locking slider with an extended cord pull.
Two full sample rounds, six weeks of development time, and one factory air freight charge later, the garment was approved. The correct specification, written clearly from the start, would have been: "YKK #5 nylon coil, closed-end, black tape, locking slider, 40 mm cord pull, teeth length 22 cm ±3 mm."
The original tech pack specification was seven words. The correct specification is twenty-three words. The difference between them was two sample rounds and a missed launch window.
If you're building out a zipper specification for a new product, our team can review tech pack entries before samples are cut and flag gaps that typically cause rejection rounds.
