Significance and Use
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.
Scope
1.1 This test method covers the measurement of the cooling energy released back to the wearer’s skin by a clothing material’s ability to move and evaporate controlled dosages of water under controlled ambient conditions using a sweating hot plate.
1.1.1 This test method establishes procedures for measuring the cooling energy during a simulated “sweating” phase and in a drying phase. Calculations are also provided to determine the drying time and how efficient the clothing material is at assisting in the evaporation of liquid water by comparing it to the maximum amount of energy that can be lost.
1.2 This test method does not address all properties that affect a clothing material’s ability to lose heat from the body. Consider measuring properties such as air permeability, insulation, and evaporative resistance.
1.3 The values in SI units shall be regarded as standard. No other units of measurement are included in the standard.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
