Inherent vs. Treated Flame Resistant Fabrics: What’s the Difference?

Many workers are presented with thermal hazards such as molten metals, arc flash, hot liquids, and flame. In environments where these hazards are present, flame-resistant (FR) personal protective equipment (PPE) is of paramount importance. When selecting such gear there are many important terms that one may be confronted with. The most common distinction is inherent fabric vs. treated fabrics.

A piece of protective equipment can be classified as an inherent fabric if it is woven using some percentage of a fiber that is itself chemically flame-resistant. These are generally oxidized fibers or fibers synthetically derived from petrochemicals that have been chemically altered. In such garments, the flame-resistant properties are inherently present in the fiber’s polymer structure and can never be lost due to washing the garment.

Protective equipment may be labeled as a treated fabric if fibers have been chemically treated to achieve FR properties, either before weaving or as a chemical finish on the garment. Some treated fabrics can lose their FR capabilities over time or with frequent or improper washing, although advances in the FR field have produced treated fabrics that retain their protective qualities for the entire lifetime of the product. The first such treated fabric was introduced in 1987, and the difference in efficacy between treated and inherent FR fabrics has been shrinking ever since. Even so, many purchasers of FR equipment turn instead to inherent fabrics or inherently flame retardant fabric due to the ongoing misconception that all treated FR garments will lose their protective properties over time.

Inherent vs. Heat Treated Fabrics

Heat-treated fabrics are materials made from the addition of flame-retardant chemicals to provide some level of flame resistance. The additive forms a strong bond with the polymer of the fiber, which is often itself not flame-resistant. This bond is difficult or impossible to remove when proper laundering and care is applied. One potential pitfall of such gear is that there is no way to visually inspect that the FR quality of the equipment is intact. If outside the useful lifetime of the equipment, or if improperly laundered, the FR qualities may be reduced or removed with almost no way to determine that this has happened.

This problem is not present with inherent FR fabrics, as the chemical properties of the fibers themselves cannot be washed out. This may cause inherent fabrics to sell at higher costs since they typically offer longer useful lifetimes. Since there is no regulatory body governing the use of this term, however, it has often been applied loosely—often to garments containing no more than 15% FR fibers blended with naturally flammable fibers. Some garments that are woven of natural fibers treated before the weaving process have even been marketed as inherent, so to some extent, the term has lost meaning.

Inherent FR Fabrics: Pros and Cons

The primary advantages of inherent FR fabrics include:

• High level of protection from thermal hazards
• Often present higher thermal protective performance (TPP) scores than treated fabrics
• Long service life
• FR properties will never wash out
• Garments will not ignite in normal O2 concentrations
• May char or expand (typically garments created with oxidized fibers) to provide increased thermal resistance under continuous exposure to a thermal hazard
• Lightweight

The most notable disadvantages of inherent FR fabrics include:

• Higher upfront cost (albeit offset by longer useful lifetime)
• Purportedly less comfortable than some treated fabrics of cotton or other cellulosic origins
• Inconsistency in application of the term ‘inherent fabric’ or ‘inherently flame retardant fabric’ that is often driven by marketing motives, rather than science and metrics relating to performance

Treated FR Fabrics: Pros and Cons

Here are some of the primary advantages of treated FR fabrics:

• Cheaper than most inherent garments
• Many available treated fabrics now provide life-of-garment FR protection
• Generally considered more comfortable
• Many available treated fabrics now only char similar to inherent fabrics, rather than combusting when exposed to a heat source
• Most treated fabrics will spontaneously extinguish a flame when the source of heat is removed

The largest disadvantages of treated fabrics include:

• Some treated fabrics will lose their protective qualities over time
• Some treated fabrics off-gas as a method of flame retardancy, producing harmful gases that in some cases include gaseous cyanide
• Many treated fabrics use increased mass as a means of increasing FR metrics such as TPP, which can increase heat strain and decrease comfort when wearing a heavier garment for extended periods
• Some 88% cotton, 12% nylon (88/12 FR) and 100% cotton blends, in particular, lose their protective qualities over time with even proper laundering
• If the flame-resistant capabilities have diminished, there is no way to tell upon visual inspection

Tex Tech: The Industry Leaders in FR Fabric Technology

Even with an understanding of the differences and usages of terms such as treated and inherent, the key factor is ultimately the safety and protective value offered to the wearer. In this regard, a more important distinction is proven vs. unproven. Tex Tech and our CarbonX brand have repeatedly proven effective in laboratory testing, as well as in the field—all with the added benefits of comfort and affordability. We work primarily with inherent fabrics.

• CarbonX’s range hoods, gloves, undergarments, and other protective garments for industrial, motor-racing, and firefighting are superior in comfort and durability and made with inherent FR fibers.
• Tex Tech provides aircraft seat fire blocking with only inherent fibers—and nothing else blended in—that lasts for many years on an airplane
• Tex Tech offers high-tech Thermal Protection System (TPS) fabrics and materials for space launch vehicles to withstand rocket burn and the thermal stresses of re-entry

Tex Tech Industries has been a leader in the advanced textile industry for over a century. Throughout this time, we have devoted enormous resources to research and development in the areas of textile and fiber solutions. We have pioneered more than 7,000 of the best performing products in the marketplace and a wide range of high-performance materials.

We provide innovative solutions for all individual fabric requirements, backed with best-in-class customer service. We invite you to contact our experienced material scientists to discuss how to discuss how Tex Tech can provide the material solutions you need.

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