School uniform testing is the laboratory verification that a primary- and secondary-school uniform meets the product standard GB/T 31888-2015 (School Uniforms for Primary and Secondary Students), layered on the mandatory textile-safety baseline GB 18401-2010 and, because the wearers include children, the mandatory children's-textile safety standard GB 31701-2015. The defining trait of school-uniform compliance — and the part most explanations miss — is that it is a three-standard stack: a product standard, a general textile-safety standard, and a children's-textile safety standard, each contributing distinct requirements that together govern whether a uniform may be sold to schools.
The Three-Standard Stack
A school uniform is, at once, a textile product, a skin-contact garment, and a children's product. Each identity pulls in a different standard, and a complete compliance report draws on all three:
| Layer | Standard | Status | What it governs |
|---|---|---|---|
| Product | GB/T 31888-2015 — School Uniforms for Primary and Secondary Students | Recommended | Classification, fiber content (cotton floor), colorfastness, seam strength, pilling, dimensions |
| Textile safety | GB 18401-2010 — General Safety Technical Code for Textile Products | Mandatory | Formaldehyde, pH, colorfastness, odor, banned azo dyes — by A/B/C class |
| Children's safety | GB 31701-2015 — Safety Technical Code for Infants and Children's Textile Products | Mandatory | Children-specific: burn performance, drawstrings/cords, plus the GB 18401 baseline |
The school uniform is governed by GB/T 31888 for what kind of garment it is, by GB 18401 for the safety of any textile, and by GB 31701 for the extra hazards a children's garment carries (a drawstring that can strangle, a fabric that can ignite). A report that cites only GB/T 31888 — or only GB 18401 — is incomplete, because each standard contributes requirements the others do not.
The Product Standard: GB/T 31888-2015
GB/T 31888-2015 is the product standard that defines what a school uniform must be. Its most distinctive requirement, and the one that separates a school uniform from a generic garment, is the cotton-content floor: for the parts of the uniform in direct contact with the skin, the nominal cotton-fiber content must be at least 35 %. The logic is wear comfort and breathability for a garment children wear for a full school day. The fiber-content result is read against the label per GB/T 29862 (Textiles — Identification of Fiber Content) and verified by the fiber-composition method.
Beyond the cotton floor, GB/T 31888 sets:
- Colorfastness — rubbing, washing (soaping), light/perspiration, each at defined minimum grades. School uniforms are washed repeatedly and worn in sun-exposed playgrounds, so colorfastness is both an appearance and a safety parameter (a dye that rubs off onto skin is a chemical-exposure risk).
- Seam strength — the resistance of the seams to opening under load, because a uniform that splits at the seam in normal play is a failed product.
- Pilling — surface-fiber-fouling resistance, again a repeated-wash-and-wear durability requirement.
- Dimensional stability — shrinkage after washing, within tolerance.
- Appearance and workmanship — the visible quality of the finished garment.
A GB/T 31888 report cites the product standard alongside each measured value, and the cotton-content result is the headline item most buyers and regulators check first.
The Textile-Safety Baseline: GB 18401-2010 (Class B)
Because a school uniform is worn in direct, prolonged contact with the skin, it falls under GB 18401-2010 class B (products in direct contact with skin). Class B sets the mandatory safety limits:
| Parameter | Class B limit (direct skin contact) |
|---|---|
| Free formaldehyde | ≤ 75 mg/kg |
| pH value | 4.0 – 8.5 |
| Colorfastness (water, perspiration, rubbing) | defined minimum grades (≥ grade 3, by item) |
| Odor | none (no unusual odor) |
| Banned aromatic amines (from azo dyes) | ≤ 20 mg/kg each, all 24 amines |
The formaldehyde, pH, colorfastness, and azo-amine requirements here overlap with the GB/T 31888 product-standard requirements — the two standards reinforce each other on these parameters — but GB 18401 sets the limit (the safety floor) while GB/T 31888 sets the product grade (the quality level). A uniform that passes GB/T 31888's colorfastness grade may still fail GB 18401's safety colorfastness floor, and vice versa; both must be checked.
The Children's-Safety Layer: GB 31701-2015
The layer that is most often omitted from school-uniform explanations — and that makes a school uniform subject to requirements a generic adult garment is not — is GB 31701-2015 (Safety Technical Code for Infants and Children's Textile Products). Because the wearers include children (the standard applies to textiles for children up to a defined age/height), the uniform must additionally meet the children's-textile requirements:
- Burn (flame-retardance) performance — children's textiles must meet defined burn-performance requirements; fabrics that ignite too readily are prohibited. This is a hazard category GB 18401 does not address at all.
- Drawstrings and cords — the length, placement, and configuration of drawstrings and cords on children's garments are restricted (no drawstrings at the neck in the youngest age band; length limits elsewhere), because drawstrings are a documented strangulation and entanglement hazard on playground equipment.
- The GB 18401 baseline, at the appropriate class — GB 31701 incorporates the GB 18401 A/B/C class structure, so the children's-textile layer does not replace the GB 18401 baseline but adds the burn and drawstring requirements on top.
For a school-uniform product covering primary grades, GB 31701 is a mandatory layer that the GB/T 31888 product standard alone does not satisfy.
Method Standards
Each parameter is measured by a defined method standard, so a compliant report is traceable:
| Parameter | Method standard |
|---|---|
| Formaldehyde | GB/T 2912.1 |
| pH value | GB/T 7573 |
| Colorfastness — rubbing | GB/T 3920 |
| Colorfastness — washing/soaping | GB/T 3921 |
| Colorfastness — perspiration | GB/T 3922 |
| Fiber content | GB/T 2910 series |
| Banned aromatic amines (azo) | GB/T 17592 + GB/T 23344 |
A report cites the method alongside each value, because the limit and the method are paired.
What Failures School-Uniform Testing Catches
The failures school-uniform testing exposes are the ones that affect a child wearing the garment for a full school day:
- Cotton content below 35 % — the uniform is less breathable and less comfortable than the standard requires; the label is also non-compliant.
- Formaldehyde above 75 mg/kg — skin irritation and sensitization risk from a residual finishing chemical.
- pH outside 4.0–8.5 — skin irritation; acidic or alkaline residues from processing.
- Colorfastness below grade — dye rubs off onto the child's skin (a chemical-exposure risk, not just an appearance problem) and fades after washing.
- Banned azo dyes releasing carcinogenic amines — the same hazard as in adult textiles, but borne by a child.
- Drawstring non-conformance — a strangulation/entanglement hazard on playground equipment.
- Burn performance failure — a fabric that ignites too readily, a hazard GB 18401 does not control.
Why the Search Results Are Off the Compliance Intent
The search results for "school uniform testing" are dominated by content that does not frame the three-standard stack:
- Lab service pages (CTI, Intertek) explain formaldehyde/pH/colorfastness and cite GB 18401 but rarely layer GB/T 31888 and GB 31701 together.
- Regulator sampling-enforcement rules (Guangzhou, Panyu, Zhanjian market-supervision bureaus) list the test items (fiber content, formaldehyde, pH) but as enforcement documents, not a compliance framework.
- Parent buying guides (quality-inspection institutes) advise "smell for odor, check the label, feel the fabric" — consumer guidance, not a laboratory compliance test.
None tells a uniform manufacturer, a school procurement office, or a regulator which three standards apply, how they stack, and what each contributes. That compliance question is what this article addresses.
Our Testing Capabilities
Beijing ZKGX Research conducts school-uniform testing across the three-standard stack:
- Product (GB/T 31888-2015): fiber content with the 35 % cotton-content floor for skin-contact parts (verified per GB/T 2910, labelled per GB/T 29862), colorfastness (rubbing GB/T 3920, washing GB/T 3921, perspiration GB/T 3922), seam strength, pilling, dimensional stability, and appearance.
- Textile safety (GB 18401-2010, class B): formaldehyde (≤ 75 mg/kg, GB/T 2912.1), pH (4.0–8.5, GB/T 7573), colorfastness, odor, and the 24 banned aromatic amines (GB/T 17592 + GB/T 23344).
- Children's safety (GB 31701-2015): burn performance and drawstring/cord conformance, plus the GB 18401 baseline at the applicable class.
- Sample types: primary and secondary school uniforms (shirts, trousers/skirts, polo shirts, sweatshirts, sport uniforms), in all fabric compositions and for all grade bands.
- Deliverable: a test report identifying the product, the applicable class (B for skin-contact), the three standards applied, each measured value with its method citation, and pass/fail against each standard's limit.
If you have a school-uniform product requiring compliance verification, contact our testing team to scope the applicable class, the children's-textile applicability (GB 31701), and the three-standard stack.
Frequently Asked Questions
What standard governns school uniform testing?
School uniforms are governed by a three-standard stack: GB/T 31888-2015 (the product standard — cotton content, colorfastness, seam strength, pilling), GB 18401-2010 (the mandatory textile-safety baseline, class B for skin contact — formaldehyde ≤ 75 mg/kg, pH 4.0–8.5, colorfastness, banned azo amines), and GB 31701-2015 (the mandatory children's-textile safety standard — burn performance and drawstrings, on top of the GB 18401 baseline).
What is the cotton-content requirement for a school uniform?
Under GB/T 31888-2015, the parts of the uniform in direct contact with the skin must have a nominal cotton-fiber content of at least 35 %. This is the headline product-standard requirement for wear comfort and breathability, verified per GB/T 2910 and labelled per GB/T 29862.
Does a school uniform need to meet GB 31701?
Yes. Because the wearers include children, school uniforms fall under GB 31701-2015 (Safety Technical Code for Infants and Children's Textile Products), which adds burn (flame-retardance) performance and drawstring/cord restrictions on top of the GB 18401 baseline. These are hazard categories that GB 18401 and GB/T 31888 alone do not address.
What is the formaldehyde limit for a school uniform?
As a direct-skin-contact garment, a school uniform falls under GB 18401-2010 class B, which limits free formaldehyde to ≤ 75 mg/kg. The class B limits also apply to pH (4.0–8.5) and to the minimum colorfastness grades.
Is the school-uniform safety class A, B, or C?
Class B (direct contact with skin). A school uniform is worn in prolonged direct contact with the skin, so it falls under the GB 18401 class B requirements — stricter than class C (non-contact) but not class A (infant). Infant and very-young-children's garments would be class A.