What Is Diaper Testing?
Diaper testing is the laboratory verification of disposable baby and adult diapers against the product, hygiene, and safety standards that govern their sale and use — primarily GB/T 28004.1-2021 (China, baby diapers), GB/T 28004.2-2021 (China, adult diapers), GB 15979-2024 (China, hygiene requirements for disposable sanitary products), GB 43631 (China, VOCs in infant diapers), plus the EDANA Guidelines for the Testing of Baby Diapers (Version 2.0, 2016) — the international industry standard for comparative diaper testing — and the underlying nonwoven-material test standards ISO 9073-13 and GB/T 24218. A complete program confirms absorption performance, leakage protection, skin compatibility, dimensional conformity, and chemical/microbial safety in one coordinated test package.
A diaper is simultaneously a fluid-handling engineering article, a skin-contacting hygiene product, and a safety-critical infant product. Each of those roles drives a separate set of tests. Beijing ZKGX Research Institute structures its diaper programs around the GB/T 28004 and EDANA clause matrix, with each measurement traceable to the exact clause being verified.
Why Diaper Testing Matters
A diaper is in continuous, occluded contact with infant skin for hours per change and multiple changes per day. The failure modes the test program targets are well documented:
- Insufficient absorption — low absorption capacity or slow absorption rate leaves skin wet, the dominant cause of diaper dermatitis
- Rewet (re-wetting) — liquid that has been absorbed is squeezed back to the skin under load (baby sitting, crawling), defeating the absorption function
- Leakage — poor cuff design, insufficient acquisition-layer distribution, or inadequate core capacity lets urine escape at the legs or waist
- Skin irritation — residual chemicals, pH drift, or VOCs in the superabsorbent polymer or nonwoven components cause contact dermatitis
- Hygiene non-compliance — microbial contamination from manufacturing, packaging, or storage exceeds GB 15979 ceilings
- Dimensional non-conformity — actual size or capacity does not match the declared size label, a labeling-fraud violation
For these reasons, diaper regulations in every major market are among the strictest in consumer-product law. Sale without a supporting test dossier means rejection at customs, withdrawal from retail, or, worse, a consumer health incident (severe diaper dermatitis, allergic reaction, microbial infection) that triggers recall and liability.
Which Standards Govern Diaper Testing?
There is no single global diaper standard; the framework is layered across product, hygiene, safety, and industry-guideline standards:
| Standard | Scope | What it answers |
|---|---|---|
| GB/T 28004.1-2021 | China — Baby diapers (replacing GB/T 28004-2011 baby portion) | Does this baby diaper meet the Chinese product standard for absorption, rewet, slip, pH, dimensions? |
| GB/T 28004.2-2021 | China — Adult diapers | Same, for adult incontinence products |
| GB 15979-2024 | China — Hygienic standard for disposable sanitary products (replaces 15979-2002) | Does the product meet microbial and production-hygiene requirements? |
| GB 43631-2023 | China — Determination of VOCs in infant diapers | Are volatile organic compounds in the diaper below safety thresholds? |
| GB/T 33280-2016 | China — Diaper specifications and dimensions | Does the size and capacity label match the product? |
| EDANA Guidelines v2.0 (2016) | International — Recommended methodology for comparative baby-diaper testing | How should a comparative consumer-test (user trial + lab tests + safety) be designed and reported? |
| ISO 9073-13 | Nonwoven fabrics — Liquid strike-through | How quickly does liquid pass through the acquisition layer? |
| GB/T 24218 series | China nonwoven test methods (absorption, penetration, liquid strike-through) | The underlying nonwoven-material test methods used in diaper component testing |
| Oeko-Tex Standard 100 (Class I) | Voluntary — textile safety for babies | Are harmful substances in the diaper's textile components below baby-product limits? |
Beijing ZKGX structures every diaper test report against this matrix so the client can see which clause of which standard each measurement satisfies — not just a pass/fail verdict.
What Are the Core Diaper Test Items?
A complete program divides into five blocks. Each item maps to a clause, and each has a measurable acceptance threshold.
1. Absorption Performance (GB/T 28004.1 §6.3 / EDANA §10)
The defining characteristic. Three sub-tests cover different aspects of fluid handling, all run with 0.9% NaCl saline solution (or referenced synthetic urine adjusted to specified surface tension):
- Absorption capacity — the total mass of saline a diaper can absorb before leakage. Per GB/T 28004.1, baby diapers must reach a grade-dependent minimum (typically ≥ 100–300 g depending on size and quality grade)
- Slip (free-surface wetting) amount — saline applied to the diaper at a defined angle and rate; the mass that runs off without being absorbed must be ≤ 20 g per the GB/T 28004.1 standard for grade-A product
- Rewet amount — under defined load applied after absorption, the mass of liquid pressed back out must be ≤ 1.0 g for grade-A product (this is the test that catches the "wet-feeling" diaper)
Sample size per EDANA: minimum 5 samples per test, reported as average ± standard deviation.
2. Liquid Strike-Through Time (ISO 9073-13 / GB/T 24218.13)
Measure the time for a defined volume of saline (typically 5 mL) to penetrate the diaper's topsheet (the layer in contact with skin). Place the specimen on absorbent paper, apply saline via pipette onto the center, and record strike-through time. Acceptance: typically ≤ 3 seconds for the first strike for grade-A diaper topsheet — fast strike-through keeps skin dry. The test is repeated (typically 4 strikes) to verify the diaper maintains acquisition performance across multiple wettings.
3. pH (GB/T 28004.1 §6.4)
Extract the diaper material in defined-volume deionized water, measure pH at standard temperature. Acceptance per GB/T 28004.1: pH 4.5–8.0 for baby diapers. pH outside this band indicates residual acid or alkali from manufacturing that could irritate infant skin. The healthy infant-skin pH is around 5.5; diaper formulations trend mildly acidic to match.
4. Dimensions and Specification (GB/T 33280 / GB/T 28004.1 §6.2)
Verify the diaper's actual dimensions and weight match the declared size and specification:
- Length and width of the diaper, at specified measurement points, within ± tolerance per GB/T 33280
- Mass per unit (weight of the finished diaper) within declared range
- Elastic properties of waist and leg cuffs — sufficient stretch to fit without constriction
- Closure system — hook-and-loop fastener peel strength sufficient to hold under load but releasable without tearing the backsheet
5. Hygiene and Microbial Safety (GB 15979-2024)
Because diapers are occluded skin-contacting products, microbial limits are strict:
| Indicator | Limit per GB 15979-2024 |
|---|---|
| Total aerobic bacterial count | ≤ 200 CFU/g (general); ≤ 20 CFU/g (for products in direct contact with broken skin or mucous membranes) |
| Total fungi and yeast count | ≤ 100 CFU/g |
| Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Candida albicans | Not detectable |
| Production environment | Defined cleanliness class for the production workshop (settle-plate and air-microbe limits) |
A common finding in market-surveillance testing is total bacterial count above 200 CFU/g, usually from contaminated recycled-pulp raw material or inadequate production-hygiene controls.
Chemical Safety — VOCs and Restricted Substances (GB 43631 / Oeko-Tex 100)
Beyond microbial limits, diaper testing includes chemical-safety screening:
- Volatile organic compounds (VOCs) per GB 43631-2023 — formaldehyde, acetaldehyde, toluene, xylene, and others; measured by headspace GC-MS. Infant diapers must meet the GB 43631 thresholds (formaldehyde, total VOCs)
- Heavy metals (Pb, Cd, As, Hg) — by ICP-MS; typically below Oeko-Tex 100 Class I (baby) limits
- Pesticides and PCPs (pentachlorophenol) — relevant where natural fibers or pulp are used
- Phthalates — relevant for printed films, elastics, and packaging
Oeko-Tex Standard 100 Class I (infant and toddler textiles) is the most widely adopted voluntary framework for these chemical-safety claims.
Performance Test (User Trial) — EDANA Guidelines §9
For comparative testing of diapers sold to consumers, the EDANA Guidelines require a user trial in addition to laboratory tests. The user trial is the dominant tool for product ranking because it captures the real-world experience that no lab test fully replicates.
Minimum user-trial design per EDANA:
- Panel size: typically ~100 users, balanced 1:1 by gender, by weight distribution, and by current-brand market share
- Duration: at least 5 days per product, ideally a full week
- Design: sequential monadic, products handed out in random order to control for weather and learning effects
- Exclusion: sick children or those with chronic skin conditions excluded from the panel
Evaluation criteria (recommended, with weighting):
- Overall preference (highest weighting)
- Leakage protection (highest weighting)
- Skin dryness (highest weighting)
- Skin friendliness
- Handling (donning and removal)
- Fastening system
- Overall fit
- Softness
The top three criteria — overall preference, leakage protection, and skin dryness — receive the highest weighting because they drive consumer satisfaction and repeat purchase. A laboratory cannot replicate these without real baby use, which is why EDANA explicitly recommends not ranking products on lab results alone.
Type Approval vs. Production Conformity vs. Market Surveillance — Don't Confuse Them
Three regimes apply to a diaper over its life cycle:
- Type approval / product registration — done once per diaper SKU when registering the product in the target market; the basis of legal sale
- Production conformity — periodic re-testing of production batches before shipment, typically a shortened set (absorption, rewet, pH, microbial)
- Market surveillance — conducted by regulators (SAMR in China, customs authorities) on diapers pulled from retail; commonly catches absorption shortfall, microbial overage, and false size labeling
A common error is treating a single type-approval pass as proof of ongoing compliance. It is not — the production-conformity regime exists precisely because pulp, SAP, and adhesives vary between production lots. Beijing ZKGX labels every report with which regime the result serves.
How Long Does Diaper Testing Take?
A complete GB/T 28004.1 + GB 15979 compliance program on a single SKU takes 5 to 8 working days, dominated by the microbial test sequence (48–72 hour incubation). Absorption tests return within 2 to 4 working days; pH and dimensional tests within 1 day; VOCs by GC-MS within 5 to 7 working days. EDANA user-trial programs are far longer — 3 to 6 weeks of recruiting, testing, and analysis — and are typically commissioned separately from the regulatory lab program.
Sample requirements: typically 10 to 15 retail packs of the same SKU for a complete GB/T 28004.1 + GB 15979 + GB 43631 package. Production-conformity uses fewer packs.
A formal test report is delivered within 5 to 7 working days after completion of each testing block, including raw data, weighing records, strike-through time logs, microbial plate counts, GC-MS chromatograms (for VOCs), and a clear statement of which clauses were met.
What Makes a Diaper Test Report Usable?
A report that only says "PASS" is useless when a regulator, retailer, or consumer challenges the quality claim. A defensible report — accepted by SAMR in China, EDANA-aligned retailers, customs authorities, and major retailer compliance reviews — must contain:
- Sample identification — brand, SKU, declared size, batch number, date of manufacture, packaging type
- Measured values with units and tolerance — not "compliant," but "absorption capacity 187 g (grade-A minimum 100 g, GB/T 28004.1 §6.3)"
- Standard-clause traceability — which paragraph of GB/T 28004.1, GB 15979, or GB 43631 each result is judged against
- Saline-solution specification — concentration (0.9% NaCl), conductivity, surface tension, all of which affect absorption results
- Microbial plate photographs and counts — actual CFU/g values, not just "passed"
- Chromatographic evidence for VOCs — GC-MS traces for any detected substance
- Signed conclusion — accredited laboratory stamp and ISO/IEC 17025 reference
Beijing ZKGX diaper reports follow this structure as standard and are issued under the laboratory's ISO/IEC 17025 accreditation framework, with each measurement traceable to a recognized national or international standard.
Frequently Asked Questions
Is diaper testing mandatory?
Yes. Sale of baby diapers in China requires GB/T 28004.1 compliance plus GB 15979 hygiene compliance; infant diapers additionally require GB 43631 VOC compliance. Sale of adult diapers requires GB/T 28004.2. Imported diapers face the same requirements at customs. Other markets have analogous frameworks — the EU requires General Product Safety Regulation compliance and chemical safety per REACH; the US applies CPSIA for children's products and FDA's OTC monograph for some adult-incontinence products.
How is diaper testing different from general baby product testing?
Diaper testing is fluid-handling focused — absorption, rewet, strike-through, leakage. Other baby-product categories test different things: baby bottle testing checks chemical migration and impact resistance, Infant pacifier testing checks tear strength and N-nitrosamines, Baby stroller testing checks mechanical and dynamic safety, and Infant cradle testing checks structural and sleep-surface safety. The common thread is infant safety, but the test methods are specific to each product's function.
Why is rewet tested separately from absorption capacity?
Because a diaper can have high absorption capacity but still feel wet. Rewet measures how much liquid is squeezed back to the skin under load — the real-world failure that drives diaper dermatitis. Two diapers with identical absorption capacity can have very different rewet values depending on how the superabsorbent polymer locks the liquid in. This is why GB/T 28004.1 tests both — capacity is the headline, rewet is the comfort signal.
Can a diaper claim "dermatologist-tested" or "hypoallergenic" without testing?
No — these are claims that must be substantiated. "Dermatologist-tested" requires documented testing under dermatologist supervision; "hypoallergenic" requires evidence of low irritation potential, typically via skin corrosion and irritation testing protocols. A claim without supporting test data is a regulatory risk under China's Advertising Law and equivalent rules in other markets.
Does an eco-friendly or biodegradable diaper need different testing?
Same regulatory tests (GB/T 28004, GB 15979 apply equally), plus verification of any compostability or biodegradability claim — typically to EN 13432 (industrial compostability) or ASTM D6400. The absorption performance tests are the same; biodegradable diapers often perform differently because their materials differ, and only testing verifies whether the performance is acceptable.
References & Further Reading
- GB/T 28004.1-2021 — Diapers — Part 1: Baby diapers (std.samr.gov.cn)
- GB/T 28004.2-2021 — Diapers — Part 2: Adult diapers (std.samr.gov.cn)
- GB 15979-2024 — Hygienic standard for disposable sanitary products (ndcpa.gov.cn)
- GB 43631-2023 — Determination of VOCs in infant diapers (std.samr.gov.cn)
- GB/T 33280-2016 — Diaper specifications and dimensions (std.samr.gov.cn)
- EDANA Guidelines for the Testing of Baby Diapers v2.0 (2016) — Recommended methodology (edana.org)
- ISO 9073-13 — Textiles — Test methods for nonwovens — Liquid strike-through (iso.org)
- GB/T 24218 series — Test methods for nonwovens (std.samr.gov.cn)
- Oeko-Tex Standard 100 — Class I baby textile safety (oeko-tex.com)