Two Chinese national standards govern the safety of apparel sold in the domestic market, and they are frequently confused with each other. GB 18401 sets general safety requirements for textile products and classifies them by skin contact. GB 31701 builds on it for infants and children, adding mechanical, chemical and labelling requirements that a general textile standard does not address. For a zipper supplier, the first governs the tape, and the second governs both the tape and the way the hardware behaves on a child's garment.

This article explains how the two standards interact, what each requires, how the testing is organised, and what a zipper specification needs to contain to satisfy them.

1. Scope and the safety classes

GB 18401 applies to textile products, including the textile components of apparel, and divides them into three classes:

  • Class A, for infants and toddlers, defined by age and by the products intended for them.
  • Class B, for products worn in direct contact with the skin.
  • Class C, for products not worn in direct contact with the skin.

A garment carries a class, and the class determines which limits apply. The zipper tape is a textile product and is assessed at the class of the garment it goes into. A tape that passes Class C but is used in a Class A garment is non-compliant, even though the tape itself was tested and passed.

GB 31701 applies to textile products for infants and children up to an age threshold defined in the standard, and it operates alongside GB 18401 rather than replacing it. A product within its scope must satisfy GB 18401 at the appropriate class and the additional GB 31701 requirements. The additional requirements include mechanical safety, such as cords and drawstrings, sharp points and edges, small parts and attachment strength; chemical requirements for certain substances in coatings and prints; and specific labelling of the safety category.

2. Key requirements relevant to zippers

The chemical requirements of GB 18401 that touch a zipper are those of the tape:

  • Formaldehyde content, with limits that differ by class.
  • pH value of the aqueous extract, within a range that differs by class.
  • Colourfastness to water, to perspiration and to rubbing, with the class determining the minimum grade.
  • Decomposable carcinogenic aromatic amines from azo dyes, which must not be detectable above the limit.
  • Odour, assessed by a panel procedure.

GB 31701 adds requirements that are more specific to children's products, and the zipper is directly involved in several of them:

  • Attachment strength. Components attached to a child's garment must resist a defined pull-off force, and a zipper puller or a decorative pull is a component. The force and the test method are set out in the standard text and should be read there rather than assumed.
  • Small parts. Components that could detach and be swallowed are assessed, and the size and security of the detached part matter.
  • Sharp points and edges. Die-cast sliders, stamped pullers and cut tape ends can present edges, and the standard requires them to be free of hazardous sharp points and edges.
  • Chemical requirements for coatings and prints. Plasticised coatings, plastisol prints and similar applications are tested for restricted substances including phthalates and heavy metals, at limits given in the standard.
  • Labelling. The product must be marked with the safety category, and the marking must match the class the product has actually been tested to.

Note that the metal parts of a zipper are not textile products, but they are still components of the garment and fall under the mechanical requirements of GB 31701. The chemical requirements for the metal are addressed through the coating and print provisions and through the general restrictions on heavy metals.

3. Test methods

The methods are named in the standards and in the referenced test method standards. A laboratory report should identify each one.

  1. Formaldehyde is determined by a water extraction and colorimetric method, reported in milligrams per kilogram.
  2. pH is measured on the aqueous extract of the sample.
  3. Colourfastness is assessed against the appropriate grey scale after the specified exposure, whether water, artificial perspiration or rubbing.
  4. Azo dye testing uses a reductive extraction followed by determination of the released aromatic amines.
  5. Phthalates and heavy metals in coatings are determined by solvent extraction and instrumental analysis.
  6. Attachment strength is measured on a tensile machine, pulling the component from the garment in the direction and at the rate specified in the method.

The report should state the class, the test method, the result and the limit. A report that reports only "pass" cannot be used to resolve a dispute about which class was applied.

4. Common non-conformities

  • The wrong safety class on the label, most often a Class B garment intended for infants that should have been Class A.
  • pH failure on tape that was dyed or washed without adequate neutralisation.
  • Azo dye failures in certain deep shades, particularly where the dyehouse has changed a recipe.
  • Phthalates in a PVC tape coating or in a plastisol print, where the compound was bought in without a declaration.
  • Detachable pullers on infant garments, failing the attachment strength requirement even though the puller was never intended to be removable.
  • Sharp edges on die-cast sliders or stamped pullers that were deburred on the sample but not in bulk.
  • A test report issued for the fabric but not for the zipper tape, leaving the tape untested.

5. Practical sourcing advice

State the class, not just the standard. "GB 18401 Class A" and "GB 18401" are different requirements, and the difference shows up in formaldehyde, pH and colourfastness limits. For infant programmes, assume Class A even where the garment might arguably be Class B, because the stricter class removes the argument.

Specify the tape's pH range and azo compliance in the purchase order, and ask the dyehouse to confirm the neutralisation step. For coated tape and printed tape, ask for the polymer and plasticiser declaration before the order, not after the test failure.

Design the hardware for the mechanical requirements. A puller that is moulded as one piece with the slider, or a puller that is captured so it cannot detach, avoids the attachment strength question altogether. Radius the edges on the drawing, and check the bulk production rather than the sample.

Test at a laboratory accredited for the relevant methods, and keep the report with the shipment file. When a clause is unclear, or when the standard refers to another document for a limit or a method, read the referenced text and cite it in the specification. The standards are the floor for the domestic market, and a customer's own specification will often be stricter.