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WARMPLUS-R Moisture-Absorbing Heat-Generating Yarn (32/1 Ne) for Winter Knits
Winter briefs from sock and underwear brands tend to ask for the same thing: more warmth, but no extra weight. A thicker fabric delivers the warmth, but it adds weight and usually feels stiffer and bulkier in wear. That is why we often suggest WARMPLUS-R, our moisture-absorbing heat-generating yarn for winter knits. Instead of relying only on thickness, it adds warmth through the way the fiber reacts with moisture from the skin.
In our experience, warmth is what gets a sample approved. However, wear comfort and how the fabric looks after washing decide whether a product sells again, and WARMPLUS-R is designed around all three.
WARMPLUS-R Quick Facts
| Product | WARMPLUS-R moisture-absorbing heat-generating yarn |
|---|---|
| Yarn count | 32/1 Ne (other counts on request) |
| Composition | 60% viscose / 40% acrylic |
| Spinning | Compact spun |
| Best for | Winter socks, underwear and base layers, loungewear, light outdoor layering |
| MOQ | From 1 kg per color |
| Packaging | Carton or plastic bag, 25 kg |
| Lead time | In stock: 1–2 days after order confirmation. Custom production: 3–15 days after order confirmation. |
How Moisture-Absorbing Heat-Generating Yarn Works
A moisture-absorbing heat-generating yarn takes up water vapor from the air next to the skin and gives off heat while it does so. In WARMPLUS-R, this effect comes mainly from the viscose.
Viscose is a cellulose fiber, so its molecules carry hydroxyl (-OH) groups that attract water vapor. Each water molecule that binds to the fiber releases a small amount of heat, and the fabric warms slightly as a result. Since the heat comes from the fiber itself, it does not depend on a surface coating.
The effect has a limit, though. The fiber only generates heat while it is still taking up moisture, and it stops once it reaches balance with the surrounding air. For this reason, you notice the warmth most soon after putting the garment on and again when you start to sweat lightly. After that, the fabric keeps you warm the usual way, by holding still air.
Used this way, the yarn lets you add warmth to a knit without simply adding grams per square meter.
Why a Viscose/Acrylic Heat-Generating Yarn Suits Winter Knits
Warmth without a heavier fabric
With a moisture-absorbing heat-generating yarn, part of the warmth comes from moisture, so fabric weight no longer has to do all the work. As a result, designers can keep a base layer or sock lighter and more flexible, so it feels less bulky on the body.
Pilling resistance for socks
Socks and next-to-skin garments rub against shoes, skin and other layers all day, so customers spot pilling quickly. WARMPLUS-R is made by compact spinning, which condenses the fibers before twisting. This gives the yarn a cleaner surface with less hairiness, and fewer loose fiber ends mean fewer starting points for pills. In testing, it reached pilling grade 3–4 (details below).
Soft handfeel next to the skin
Viscose gives the yarn a smooth, soft touch, while acrylic adds loft and warmth. Together they suit products where softness matters as much as warmth, such as base layers, loungewear and socks.
Where WARMPLUS-R Works Best
- Winter underwear and base layers: a warmer feel without extra bulk.
- Socks: as a yarn for winter socks, it combines warmth with a cleaner surface after wear.
- Loungewear: a soft, cozy hand for winter homewear.
- Light outdoor layering: base-layer systems and mid-layer concepts.
When you contact us, start with the end use (socks or base layers). Then share your target fabric weight and finishing route, because these two details usually shape the final fabric more than any single yarn spec.
WARMPLUS-R Heat-Generating Yarn Test Results
We prefer to talk about performance with the test method on the table. So far, WARMPLUS-R has two reports:
| Test | Method | Result |
|---|---|---|
| Heat generation (report dated September 10, 2025) | BQE A 035-2018 | Maximum temperature rise of 5.3 °C, compared with 1.5 °C for the control sample (a difference of 3.8 °C) |
| Pilling resistance | GB/T 4802.1-2008 | Grade 3–4 on a 1–5 scale, where 5 means no pilling |
In the heat test, the lab raised the relative humidity around the specimen from 40% to 90% at 20 °C and recorded its temperature for 15 minutes. The result shows how much warmer the WARMPLUS-R sample became than the control under those conditions. It does not measure body temperature, and it does not cover performance after washing.
Knit structure and finishing still affect the final result. Treat these reports as a reference, and then confirm performance on your own construction during sampling.
A Fast Sampling Plan
If you need to decide quickly, this four-step plan keeps the comparison simple:
- Knit one construction you already sell, so you have a baseline.
- Knit a lighter version in WARMPLUS-R to compare warmth against weight.
- Wash-test both for pilling early instead of leaving it to the last step.
- Finally, compare them in a wear trial as well as in lab tests.
Keep the gauge, dye route and finishing the same for both samples. Otherwise, you cannot tell whether a difference comes from the yarn or from the process.
Request a Quote
Tell us the end use (socks, base layers or loungewear), target gauge, fabric weight, color list, and whether you need stock or custom production. With these details, we can quote accurately and suggest a starting construction.
FAQ
What is moisture-absorbing heat-generating yarn?
It is a functional yarn that releases heat as it absorbs water vapor. People also call it hygroscopic heat yarn or simply heat-generating yarn. In WARMPLUS-R, the viscose is the main source of this effect, while the acrylic adds loft and warmth.
Does moisture-absorbing heat-generating yarn keep generating heat all day?
No. It generates heat only while the fiber is still absorbing moisture, so the effect is strongest soon after you put the garment on and when you start to sweat. After that, the fabric keeps you warm by holding still air, like any other knit.
Is WARMPLUS-R suitable for socks, base layers and loungewear?
Yes, these are its main uses. Socks gain from the warmth and the cleaner surface, while base layers and loungewear gain from the soft handfeel. For socks, tell us your needle count and sock weight so that we can suggest a starting construction.
What does pilling grade 3–4 mean for buyers?
Pilling is rated from 1 to 5, where 5 means no pilling, so grade 3–4 sits in the mid-to-good range. Always read a grade together with its test method. Since our result comes from GB/T 4802.1-2008, compare it only with results from the same method and a similar fabric construction.
Will dyeing or finishing change the performance?
It can. Dyeing and finishing often change handfeel and surface appearance. That is why we suggest approving the lab dip on both the yarn and the finished fabric, and then checking key properties after your real process.
Can we use “heat-generating” claims on consumer products?
You can, but match the wording to your market’s labeling rules and to what the test actually measured. Our heat test supports a claim about fabric temperature rise under the stated conditions. By contrast, a thermal resistance test such as ISO 11092 measures insulation, so it cannot support a heat-generation claim on its own.
Can we order small lots or mix colors?
Yes. The MOQ is 1 kg per color, so you can run small knit trials or lab dips before you scale up. Because the minimum applies per color, you can also combine several colors in one sampling order.
Can you recommend a knit structure for warmth and softness?
Share your product category, such as socks or base layers, and the hand you want. We will then suggest a practical starting construction for development.