4.1 A clothing material's ability to assist in the evaporation of liquid sweat by managing liquid moisture is of considerable importance when trying to maximize cooling and comfort benefits to the wearer while active. Understanding how much energy is released back to the skin is critical in determining their suitability for use in fabricating protective clothing systems or athletic wear.

4.1.1 The cooling energy released back to the wearer can be significantly affected by environmental conditions. Extreme care must be taken when using standard results measured under standard testing conditions to determine a material's suitability for use in conditions outside the testing conditions.

4.2 This test method accounts for a clothing material's ability to assist in evaporating liquid water during a sweating phase, as well as its ability to dry after the cessation of sweating.

4.2.1 A large amount of cooling energy released from clothing materials during active work (sweating) is often seen as a positive, as it would assist in keeping the body cooler.

4.2.2 A large amount of cooling energy released from clothing materials after active work (no sweating) is often seen as a negative, as it known to cause a chilling effect to the wearer.

4.2.3 The longer it takes for a clothing material to dry after becoming wet is perceived as a negative, as it increases the potential for chilling the wearer.

4.3 The thermal interchange between people and their environment is, however, an extremely complicated subject that involves many factors in addition to the steady-state resistance values of fabrics, films, coatings, foams, and leathers, including multi-layer assemblies. Therefore, the cooling provided from liquid evaporation may or may not indicate relative merit of a particular material or system for a given clothing application. While a possible indicator of clothing performance, measurements produced by the testing of fabrics have no proven correlation to the performance of clothing systems worn by people. Consider measuring other clothing material properties such as thermal resistance and evaporative resistance when evaluating a clothing material.

4.3.1 The thermal resistance and evaporative resistance of clothing materials are measured with a standard sweating hot plate in an environmental chamber in accordance with Test Method F1868.