Zipper teeth, slider and tape
Whether the teeth run in one line, the slider moves under a light pull, and the tape stays flat.
The reading sequence
3 steps, starting at surface and finish and running to check the tape at the chest curve and at both ends. Evidence on this point is read at E1, and 3 of the 3 steps carries a condition that ends the assessment outright.
Read the slider and the pull for markings and material
Establish what the zip is and whether it is the part the listing names, before judging how it moves.
Evidence: E1 — one macro photo of the slider face and one of the pull, both with the zip closed, in indirect light at about 10 cm
- Stamping on the slider is crisp, with characters of even weight and depth.
- The slider body is metal with no moulding seam, and the pull hangs straight.
- Stamping is shallow but legible, or the pull is stamped sheet metal with a burr at the edge.
- The pull hangs at an angle while the slider face is clean.
- A zip sold as branded carries no marking at all on the slider.
- Characters are uneven or misspelled, or a plastic slider sits on a zip sold as metal.
Run the slider up and down on video
Test the action with one hand at wearing tension, which is the only test that separates a stiff zip from a failing one.
Evidence: E1 — one continuous video with the whole zip in frame: closed, then opened and closed twice with one hand, no cutting between passes
- The slider travels the full length with one hand and no change of grip.
- It stops where it is released, and the teeth close behind it with no gap.
- One stiff point at the chest curve needs a second, firmer pull.
- The slider drifts back about a centimetre after being released.
- The slider needs two hands or a hard tug at any point on the run.
- Two or three teeth stay open behind the slider, or the pull jams in the slider body.
Check the tape at the chest curve and at both ends
Decide whether the tape was set flat along the curve, since a tape sewn under tension waves and lifts the teeth off line.
Evidence: E1 — two photos: the chest curve with the jacket on a hanger, and the top and bottom ends of the zip with the tape ends in frame
- Tape lies flat with no wave, and the stitch line sits 2 mm from the teeth along its length.
- Both ends finish with a fabric tab or a bartack and no loose thread.
- A single shallow wave shows in the tape at the chest curve.
- One end carries a thread tail under 5 mm.
- The tape puckers into visible waves that lift the teeth off their line.
- The tape is stitched through the teeth, or an end is raw with the teeth cut open.
Why the thresholds sit where they do
A zip is the one part of a jacket that is used several times a day, so a defect that is invisible on a hanger shows up within a week. The three steps run from identity to action to construction, because each can pass while the next fails: a correctly branded zip can still bind, and a smooth zip can still be set into a tape that was sewn under tension. The chest curve is checked by name because that is where a straight tape meets a curved panel, and it is the point where most zips on this kind of jacket start to catch. Passing the slider test with one hand at wearing tension is the threshold, since a two-handed pull means the zip will jam once the jacket is on.
Common misreads
3 pairs recorded for this point. Each runs in both directions: 2 findings that looks worse than it is, and 1 that looks better.
- looks like Return actually Pass
A zip that feels tight on a jacket straight out of a bag. New teeth and a stiff tape loosen within a few uses, and a firm first pull is not the same as a bind.
- looks like Pass actually Query
A smooth zip shown in a short clip that starts mid-run. The stiff point on this kind of jacket sits at the chest curve, which a clipped video tends to leave out.
- looks like Return actually Query
A slider with a shallow stamp. Several makers stamp lightly on plated bodies, and shallow characters alone do not mean the part is a copy.
Check this point against what you were sent
Insufficient evidence
Nothing decided on zipper brand and action yet: 0 of 3 steps have been read.
0 of 3 steps judged
| Step | Reading | Evidence | Stop met |
|---|---|---|---|
| 1. Read the slider and the pull for markings and materialneeds E1 | The slider carries no marking on a zip the listing names by brand, and the seller will not name the maker in writing. The part in hand is not the part in the description, and nothing later in the sequence changes that. | ||
| 2. Run the slider up and down on videoneeds E1 | The chain opens behind the slider during a single pass. Teeth that have been forced apart do not close again, and the zip separates on the next pull with the jacket on. | ||
| 3. Check the tape at the chest curve and at both endsneeds E1 | The tape is stitched through the teeth, or an end is left raw with the teeth cut open. Either one lets the slider jump the chain, and it happens through use rather than through rough handling. |
Sources and checks
- Public community thread — Threads where a jacket zip failed or jammed within the first monthn=42
- Editor analysis — One-hand pull at wearing tension set as the pass thresholdno sample
Last checked · next review due · status current.
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