Thermal Properties of Fabric

Fabric, often referred to as textiles when the fabric is manufactured, has been used for a number of insulation and heat-related purposes. While there are hundreds of different types of fabric, from plain cotton to Nomex, these fabrics all have thermal properties that are measured in similar ways. Often it's these properties that make one fabric more desirable for a certain purpose over another.

Thermal Conductivity

• Thermal conductivity is one of the important thermal properties of a fabric. This can be thought of as how well a fabric "breathes." A fabric that has a high thermal conductivity easily lets heat pass from a hot side (say the body of the wearer) to a cooler side (the air on the other side of the shirt). For clothing, especially clothing that's meant for warmer weather, thermal conductivity is a very important factor.

Heat Resistance

• Another factor, one which is the inverse (opposite) of thermal conductivity, is the fabric's heat resistance. As it might imply, a fabric's heat resistance is how much it resists heat being transferred through it. So if a firefighter's jacket has a high heat resistance, then it will not only keep in the heat from his body temperature, but it will also stop the heat from the flames in a building from getting through his coat to burn his skin.

Thermal Resistance

• While it might seem similar to heat resistance, a fabric's thermal resistance refers to the fabric's thickness. Even fabrics with a high thermal conductivity like cotton may have a higher thermal resistance if that cotton is put in many layers to increase its thickness. So a fabric's thermal resistance is how long it actually takes a heat transfer to occur as heat moves through the fabric in one direction at the speed given by that fabric's heat conductivity.