When it comes to thermal protection, the thermal barrier provides the majority of protection from the intense heat and has the greatest degree of influence on isolating the body from the heat source. Most thermal barriers consist of a thin woven fabric known as the face cloth that is quilted to a nonwoven fabric called batt. The total comfort and user experience with the protective clothing ensemble can be good or bad based on the thermal barrier.
While there is little to do with protection from the face cloth, the ability to work comfortably and don and doff the garment quickly is affected. Slick face cloths make it easier to move in the garment. The use of filament yarn is one of the factors that determine the slickness; the other is the design of the weave which can be adjusted to increase the slickness effect. Moisture absorbing and quick drying face cloths can also enhance comfort.
The batt can be either needle-punch or spunlace.
Needle-punch batts are typically one fairly thick layer, while spun lace batts are much thinner and usually two layers. Needle-punch batts are less expensive and less breathable but can have higher insulative values from heat. Spunlace batts provide improved flexibility, greater ease of movement, higher Total Heat Loss (breathability), but less thermal protection.
It’s easy to understand why so many fire fighters care about their outer shell. If the outer shell fails, the rest of the system will likely be compromised as well. However, all three components deserve your attention. Each is there for a reason, and each contributes to the performance of the garment. Understand each component and how performance is affected when the combination is changed. Carefully consider all three components and select the ones that best fit your needs when writing your next spec.