Qmax

Definition and Overview

qmax measures the maximum heat flux at the moment a heated plate simulating skin touches the fabric, and quantifies cool-to-the-touch sensation. It is generally expressed in watts per square centimeter, and the larger the value, the more likely it is to feel cool the moment it is touched.

It is not a fabric weave name, material name, or processing name, but a performance evaluation value that represents heat transfer under specific test conditions. Therefore, even with the same material, the value varies depending on yarn usage, density, thickness, surface shape, and finishing process.

Characteristics and Sensation

Fabrics with a high qmax are more likely to quickly draw heat from the skin, creating an initial impression of smooth, cool touch. This tendency may appear in fabrics with a smooth surface and large contact area, or in materials and finishes that conduct heat well.

However, qmax is an indicator of the sensation immediately after touch. It does not by itself guarantee coolness during wear, breathability, water absorbency, moisture absorbency, moisture permeability, skin release, or how easily moisture escapes inside clothing. It also does not necessarily match visual gloss, sheerness, or thickness.

• The higher the value, the stronger the cool sensation on contact generally tends to be.
• The perceived sensation changes depending on conditions such as being damp with sweat, layered clothing, the presence or absence of wind, and the wearer's body temperature.
• Fabrics with large surface irregularities and little contact with the skin do not necessarily have a high qmax, even if they release from the skin well.

Main Applications

It is referenced in spring and summer clothing, bedding, innerwear, sports applications, and other products that want to emphasize coolness on contact. For shirts, cut-and-sew items, pants, dresses, and linings, balance with functions other than coolness should be checked according to the application.

If you want coolness on the side that directly touches the skin, not only the outer fabric but also the material and structure on the reverse side are important. When considering clothing comfort, breathability, quick-drying performance, stretch, sheerness, and drape should also be evaluated together.

How to Choose and Handling Precautions

When comparing values, confirm whether they were measured using the same test method, test environment, and sample condition. Values obtained under different test conditions cannot be compared simply. In the planning stage, evaluating the hand feel of swatches and then checking wear performance through prototypes makes judgment easier.

qmax itself is not an indicator of fabric shrinkage, wash durability, or sewing performance. If the texture or surface condition changes after washing, the contact feel may also change, so shrinkage rate and wash durability should be checked. For slippery surfaces or thin fabrics, stitching shift, puckering, and seam waviness should be checked in advance with trial sewing.

Differences from Similar Terms

Cool to the touch is a general expression for the property of feeling cool when touched, and qmax is one of the representative numerical values used to evaluate it. When indicating or promoting cool-to-the-touch performance, the test conditions and basis for the claim must be confirmed.

Water absorbency and quick-drying performance refer to the ability to absorb sweat or moisture and dry easily, while breathability refers to how easily air passes through. All are related to summer comfort, but they evaluate different aspects from the heat transfer immediately after touch that qmax measures.

Frequently Asked Questions