Moisture Absorption Cooling Test | GB/T 47782

Moisture can create two different thermal effects in a textile. A hygroscopic fiber may release heat as it takes up water vapor. Liquid sweat, however, can lower a fabric’s temperature when it spreads over a larger area and evaporates. This second process is moisture absorption cooling.

The difference matters in sportswear, base layers, socks, summer knitwear and other products worn during activity. A cool touch during the first few seconds does not prove that a fabric will keep cooling after sweating begins. Likewise, high moisture regain does not automatically produce a strong cooling result. Fiber chemistry, fabric structure, airflow, humidity and washing all affect what happens after moisture reaches the textile.

GB/T 47782-2026 gives laboratories and product teams a common method for testing and grading this moisture absorption cooling response. It also gives buyers a better way to question claims such as “5°C cooler.” A local temperature decrease on a controlled specimen is useful test data, but it is not the same as a 5°C decrease in skin or body temperature.

Why Moisture Can Heat or Cool a Textile

Moisture absorption heating and moisture absorption cooling may sound contradictory. They occur under different moisture conditions and rely on different heat-transfer processes.

Hygroscopic heating begins with water vapor

Some fibers attract water molecules from humid air and from the microclimate between clothing and skin. When those molecules bind to available sites in the fiber, the sorption process can release a small amount of heat. Fiber composition, moisture regain, ambient humidity, fabric weight and trapped air influence the size and duration of that effect.

A dense winter knit may retain the released heat better than an open summer construction. That is the working route behind a moisture-absorbing heat-generating yarn. It does not produce unlimited heat, and the finished fabric still needs a suitable construction and an agreed heat-generation test.

Moisture absorption cooling begins with liquid water

During heavier exercise, sweat reaches the textile as liquid water. A useful summer fabric takes up that liquid, moves it away from the original wet point and spreads it over more surface area. Water then has a larger area from which to evaporate.

Evaporation requires latent heat. Part of that heat comes from the wet textile and the nearby surface, so the measured fabric temperature can fall. Air movement normally helps evaporation, while high humidity and a poorly ventilated clothing layer slow it down.

Absorbency alone is not enough. A hydrophilic yarn in a dense construction may hold water without spreading or drying it efficiently. A softener or other finishing change can also alter the wetting route. For that reason, moisture absorption cooling should be confirmed on the finished fabric rather than inferred from the yarn name.

Moisture absorption cooling process showing fabric absorbing and spreading sweat before evaporation lowers fabric temperature

Development question	Hygroscopic heating	Moisture absorption cooling
Main moisture form	Water vapor in humid air or the clothing microclimate	Liquid sweat or controlled test water
Main heat direction	Sorption can release heat	Evaporation absorbs and removes heat
Typical product direction	Thermal socks, base layers and winter knits	Summer socks, activewear, underwear and lightweight knits
Critical fabric factors	Fiber chemistry, moisture regain, fabric mass and insulation	Wetting, spreading, evaporation area, airflow and drying behavior
Evidence needed	A heat-generation method agreed for the project	A cooling method such as GB/T 47782-2026 when applicable

Why GB/T 47782-2026 Matters for Moisture Absorption Cooling Claims

Moisture absorption cooling figures become difficult to compare when suppliers use different water doses, test conditions, specimen faces or temperature positions. A phrase such as “wearing it feels 5°C cooler” says very little unless the method and measured parameter are also clear.

China published GB/T 47782-2026, Textiles—Testing and evaluation for cooling performance by absorption, on July 2, 2026. It is scheduled to take effect on February 1, 2027. The official national standard record identifies it as a recommended national test-method standard. Anta (China) Co., Ltd. is listed first among the drafting organizations.

Because it is a recommended GB/T standard, it is not automatically mandatory for every textile. A buyer, brand, laboratory or contract can still adopt it as a purchasing or claim-verification requirement. For a bulk order, the method gives the mill, laboratory and garment team one reference point for the sample and its claim.

The moisture absorption cooling test answers two practical questions: what is the maximum specimen temperature decrease after wetting, and what is the average temperature decrease during the first 10 minutes? Keeping the liquid dose, specimen condition and measurement route consistent makes product comparisons more meaningful.

How the Moisture Absorption Cooling Test Works

The test places a conditioned textile specimen on a constant-temperature hot plate inside a controlled test system. After the specimen reaches equilibrium, the operator applies a measured dose of Grade 3 laboratory water at the center and records the temperature change at the wetting point.

Two results describe the moisture absorption cooling performance:

Maximum temperature decrease: the largest temperature drop recorded after the water is applied.
Average temperature decrease within 10 minutes: the average drop during the defined 10-minute period.

Both values matter. A sharp early drop can produce a high maximum, but the result may recover quickly. The 10-minute average shows what happened across the stated period; it does not mean that the temperature continued falling for all 10 minutes.

1. Sampling and wash preparation

For fabric, take at least 0.5 m of full-width material and avoid the area within 2 m of the roll end. For a finished textile product, take at least one complete unit. Divide the material into Sample A for before-wash testing and Sample B for testing after the specified washing pretreatment.

The wash procedure must stay with the report. Detergent, temperature, cycle and drying route can affect a finish or relax the construction, so an “after wash” statement without a defined procedure is not enough for bulk approval.

2. Cutting and mounting the specimens

Cut three representative specimens for each required condition. Each piece measures 150 mm × 130 mm. Avoid obvious defects or distorted areas unless the test is investigating that specific condition.

Condition the specimens as required by the method. Mount each piece smoothly without stretching, wrinkling or deforming it, then place it flat on the hot plate. Place the side normally worn next to the body facing upward, unless the product specification identifies another tested face.

Start temperature monitoring and allow at least 30 minutes for equilibrium. Handling matters here. A stretched specimen can change the pore structure and water-spreading area, which may affect the recorded curve.

3. Preparing the Grade 3 water

Place the Grade 3 laboratory water in a thermostatic water bath and hold it at 35 ± 1°C. This value applies to the water, not to the test chamber or hot plate. Grade 3 water keeps the liquid quality consistent between specimens; it is not tap water or artificial sweat.

After the specimen reaches equilibrium, record its initial temperature to the nearest 0.1°C.

4. Applying the liquid and recording the result

Use a micropipette to take 0.2 mL of the prepared water. Apply it gently at the center of the specimen, keeping the pipette tip no more than 1 cm above the surface. The operator then records the temperature curve and calculates the required maximum and 10-minute average decreases.

The tested face and drop position are not minor details. A one-way moisture-transfer fabric may behave differently when reversed, while an off-center or splashed dose can create a different wetting area. For laboratory reporting, sampling, pretreatment, instrument settings and calculations must follow the issued standard.

Moisture Absorption Cooling Grades

GB/T 47782-2026 divides moisture absorption cooling performance into Grade I, Grade II and Grade III. Grade III is the highest. A specimen must meet both the maximum-decrease threshold and the 10-minute average threshold for the stated grade.

Performance grade	Maximum temperature decrease	Average temperature decrease within 10 min
Grade I	≥ 7.0°C	≥ 6.0°C
Grade II	≥ 8.0°C	≥ 7.0°C
Grade III	≥ 9.0°C	≥ 8.0°C

The lower qualifying value controls the grade. A specimen that reaches a Grade III maximum but only a Grade I 10-minute average does not qualify as Grade III.

When a product carries a grade under this method, both the before-wash and after-wash results must meet the corresponding requirements. For example, a fabric should not be presented as Grade III when the unwashed specimen reaches Grade III but the washed specimen falls to Grade I.

What a Passing Result Does Not Prove

The moisture absorption cooling result describes the temperature response at the wetted point on a textile specimen under controlled laboratory conditions. It does not measure core body temperature, and it does not prove that the wearer’s skin will fall by the same number of degrees.

A Grade III maximum decrease of at least 9.0°C must therefore remain a specimen result. Rewriting it as “reduces body temperature by 9°C” changes the meaning of the test.

The grade also does not replace other performance checks:

Initial cool touch: the first contact sensation relates to heat transfer when skin touches the material. It is often assessed with a Q-max-type method. The mechanism described for cool sensation cooling fabrics needs separate evidence and claim wording.
Liquid moisture management: wicking, spreading and one-way transport answer related but different questions. AATCC TM195 can support fabric development, but it is not equivalent to the GB/T 47782-2026 temperature-decrease method.
Drying time: a fabric may spread water well but dry slowly in humid or still-air conditions.
Air permeability and thermal resistance: both affect wearing comfort, but neither is established by the moisture absorption cooling grade.
Bulk consistency: the report applies to the identified specimen, construction, finish, wash condition and lot.

From Yarn Trial to a Stable Bulk Result

From our factory view, the yarn cone is only the starting point. Fiber blend, yarn count, twist, knit structure, stitch length, fabric weight, elastane ratio, dyeing, heat setting and softener can all change the route taken by liquid water. Two fabrics made with the same cooling yarn may therefore produce different temperature curves.

In our sample room, every sock trial stays with a sample card showing the machine gauge, yarn lot, stitch length, plating arrangement and elastic tension. On an 18G machine, for example, a tighter stitch or a different elastic feed can change fabric thickness and wetting area even when the same yarn is used. These settings need to remain attached to the trial; hand feel alone cannot approve the next lot.

We also compare the greige trial with the finished fabric because dyeing, heat setting and softening can change how quickly water spreads. After washing, we look beyond the cooling number. Uneven wetting, dimensional movement, surface fuzz or a large hand-feel shift may still create a bulk problem even when the specimen reaches the target grade.

A practical development route

Define the end use. A running sock, close-fitting base layer and loose summer knit do not need the same balance of cooling, drying and durability.
Set the claim boundary. Decide whether the target is initial cool touch, moisture absorption cooling, moisture management, quick drying or a clearly defined combination.
Lock the test route. Record the method edition, target grade, tested face, washing procedure, required cycles and report format.
Make a controlled trial. Keep the yarn lot, construction, machine settings, finished weight, color or lab dip and finishing route with the sample.
Test and confirm bulk. Separate before-wash and after-wash pieces, approve a traceable specimen, then compare a representative bulk sample with the agreed construction.

A successful moisture absorption cooling trial in a pale lab shade should not automatically cover a dark bulk shade if the finishing route changes. The same caution applies when the mill alters fabric density, elastane feed or softener. Where the change may affect wetting and evaporation, test the confirmation sample again.

What Buyers Should Request in the Test Report

A statement that a fabric “passed the moisture absorption cooling test” is not enough for purchasing or claim approval. The report should make the tested construction traceable.

Full standard number and edition
Sample code, composition, yarn count, fabric construction, weight, color and finish
Tested face and specimen orientation
Before-wash and after-wash status
Exact washing and drying procedure
Maximum temperature decrease and 10-minute average
Number of specimens and required individual or averaged readings
Laboratory name, report date and instrument reference
Lot or trial reference connecting the report to the goods being purchased

Before bulk approval, our team matches the tested specimen to the yarn lot, fabric construction and finishing route. If those details no longer match production, the old report should not be used as proof for the changed fabric.

Common Questions About Moisture Absorption Cooling

Can a fabric absorb moisture and still feel warm?

Yes. Water-vapor sorption can release heat, while liquid held in a fabric without enough evaporation may feel warm and clammy. Cooling depends on how the liquid wets, spreads and evaporates, not only on how much the material absorbs.

Does Grade III mean that the wearer becomes 9°C cooler?

No. Grade III requires a maximum specimen temperature decrease of at least 9.0°C and a 10-minute average decrease of at least 8.0°C under the defined method. Those are local textile measurements, not reductions in skin or core body temperature.

Can a cooling yarn guarantee the final fabric grade?

No. The yarn creates one part of the moisture pathway, but fabric construction and finishing determine how that pathway works in the tested specimen. We confirm the finished construction rather than transferring a yarn claim directly to every fabric.

Is a quick-dry report enough?

No. Drying rate and moisture management provide useful supporting information, but they do not measure the same temperature response as GB/T 47782-2026.

Why do before-wash and after-wash results both matter?

Washing may remove part of a finish, relax the construction or change surface wetting. Testing both conditions shows whether the stated moisture absorption cooling grade remains after the specified pretreatment.