What is qmax? Understanding Contact Cool Feeling Testing
As awareness of heatstroke prevention continues to grow, evaluating how “cool” a material feels to the touch is gaining increasing attention. Although many testing devices for measuring qmax have entered the market in recent years, the original principle behind qmax was first realized through the KES-F7 Thermo Labo—the first testing instrument to quantify the sensation of coolness as a numerical value.
In this article, we take a closer look at qmax and how contact cool feeling is tested today.
What is Contact Cool Feeling and qmax?
The sensation of “coolness” or “warmth” felt when skin touches a material is technically referred to as contact warm/cool feeling. This perception is influenced by the amount of heat transferred from the skin to the material.
The standard indicator used to evaluate this sensation is qmax (peak heat flux), which can be measured using the KES-F7 Thermo Labo and the KES-QM Warm/Cool Feeling Measurement Tester.
qmax was defined by Dr. Sueo Kawabata of Kyoto University in the 1970s during the joint development of the original Kawabata Evaluation System™ (KES™). Today, you may see variations like Q-MAX, Qmax, or QMAX—but the correct notation per JIS and other global standards is qmax.
About the Standards
The Japanese Industrial Standard (JIS) “Testing Method for Contact Cool Feeling of Textile Products” was drafted based on the KES-F7 Thermo Labo. Similar guidelines were adopted in other countries, such as:
- GB/T 35263-2017 – China’s standard for evaluating cool touch textiles
- CNS 15687, L3272 – Taiwan’s method for testing instantaneous cool feeling
The Evolution of qmax Testing
In 1977, Dr. Kawabata found a strong correlation between initial peak heat flux and perceived contact temperature. This led to the development of the first Thermolabo system to analyze heat transfer in textiles.
KATO TECH later collaborated with Dr. Kawabata to develop the Thermolabo-II, the prototype for today’s KES-F7 Thermo Labo. This instrument evaluates:
- qmax (peak heat flux)
- Thermal insulation
- Thermal conductivity
More than 50 years later, it’s still widely used by manufacturers and research institutions worldwide. The KES-QM Warm/Cool Feeling Measurement Tester builds on this legacy by automating qmax testing based on the same core principles.
Proven Reliability and Global Use
From textile R&D labs to commercial QA operations, KES systems are trusted around the world. With decades of proven reliability and accuracy, Seika Machinery and KATO TECH continue to support innovation in tactile performance analysis and fabric evaluation.
Interested in learning more?
KES Systems: Fabric Touch & Performance Analyzers Product Overview
