The Risk Is Not the Zipper

A metal fragment in a garment is a safety event, not a quality defect. It can injure a wearer, trigger a recall, and end a retail relationship in a single afternoon. The fragment rarely comes from the zipper itself. It comes from a broken needle, a blade, a staple or a maintenance tool upstream, and it travels through the process inside a carton until someone finds it against a child's skin.

Because the cause is upstream, a foreign matter clause cannot be limited to final inspection. It has to describe the equipment, the frequency, the response to a find, and the records that prove the response happened. A clause that says "goods shall be free from metal contamination" is a wish, not a control.

What the Clause Must Specify

  1. Equipment. Conveyor-type metal detector with ferrous and non-ferrous capability, or X-ray where the product geometry defeats a detector. State the model family and the aperture size.
  2. Sensitivity. The smallest test piece that must be detected, in millimetres, for ferrous, non-ferrous and stainless steel. A typical requirement is 1.0 mm ferrous and 1.5 mm non-ferrous.
  3. Frequency. 100 percent of production, not sampling. Detection is a pass-through control, and a sampled control protects nothing.
  4. Challenge testing. Test pieces passed at the start, middle and end of every shift, with results recorded.
  5. Rejection handling. Rejected units quarantined, re-scanned, and the cause investigated before the line restarts.
  6. Needle control. Numbered needles, issue and return logs, and a documented search procedure for every break.
  7. Records. Retention period, typically three years, and the buyer's right to audit them.
  8. Consequence. What happens if a fragment is found downstream, including containment, notification and cost allocation.

Clause Block

CLAUSE 14 - FOREIGN MATTER AND NEEDLE CONTROL
14.1 All finished goods pass through a conveyor metal
     detector at 100% of output. Detector log retained
     for 3 years and open to Buyer audit on 48 hours'
     notice.
14.2 Sensitivity: 1.0 mm ferrous, 1.2 mm non-ferrous,
     1.5 mm stainless. Verified with certified test
     pieces at start, middle and end of each shift.
14.3 Any failed unit is quarantined in a locked bin,
     re-scanned individually, and released only after
     the cause is identified and recorded.
14.4 Needles are numbered and signed out. A break stops
     the line; the broken parts and the complete needle
     are recovered before restart. Search record signed
     by the line supervisor.
14.5 A fragment found at Buyer's premises triggers:
     (a) notification within 4 hours;
     (b) containment of all goods from the same line
         and shift;
     (c) 100% re-inspection at Seller's cost;
     (d) root cause report within 5 working days.
14.6 Seller bears the cost of recall, sorting and
     freight arising from confirmed contamination.

The Broken Needle Protocol

The protocol matters more than the detector, because most fragments enter the product before the detector is reached and some detectors are defeated by the mass of the zipper itself. A workable protocol has five steps, and every step produces a signature.

  1. Stop the machine and the line immediately; do not finish the piece in progress.
  2. Recover every fragment, including the point and the shank, and fit them to the broken needle to confirm the set is complete.
  3. If any part is missing, quarantine the output since the last verified needle check and search the machine, the floor and the waste bin.
  4. Record the needle number, machine, operator, time, fragments recovered and the search result.
  5. Restart only after the supervisor signs the record; a missing fragment means the quarantined output is re-scanned piece by piece.

Detector Limits and the Honest Conversation

Metal detectors are not absolute. A zipper with a metal chain and a metal slider creates a signal that can mask a small fragment, and the aperture size limits what can pass through. Where the product makes detection unreliable, the contract should require X-ray or a documented alternative control, and it should say who pays for the change.

It is also worth agreeing what "detected" means. A test piece taped to the outside of a carton proves the detector alarms; it does not prove the detector sees a fragment inside a folded tape. Challenge pieces should be buried in the product, at the position and orientation that the real risk would take, and the record should say so.

Records, Audit and the Cost of Proving It

The clause is only as strong as the log behind it. Ask for the detector log, the needle issue register and the quarantine records as part of routine supplier review, not only after an incident. A factory that cannot produce a log within an hour of a request has a control that exists on paper.

Donglong runs needle control audits at each of its finishing lines because the cost of one incident outweighs years of logging. Buyers auditing a supplier should ask the same question the auditor asks: show me last Tuesday.

A Note on Use

This article is general technical and commercial reference, not legal advice. Detection limits, record retention and recall liability must be set against the destination market's safety rules and confirmed with your technical and legal teams before being written into a supply contract.