FR clothing is specialized protective equipment designed to self-extinguish when exposed to a flame source, reducing burn injuries. A common concern is whether these garments maintain their size through laundering. FR clothing can shrink, especially when made from natural fibers like cotton or cotton blends. Manufacturers engineer these garments to minimize dimensional change, and following specific care guidelines reduces the risk of excessive shrinkage. Understanding the fabric type and the causes of size reduction helps maintain the garment’s fit and protective qualities.
The Difference Between Treated and Inherently Flame-Resistant Fabrics
Treated FR Fabrics
The potential for an FR garment to shrink relates directly to its fiber composition and how flame resistance is achieved. Chemically treated FR fabrics often use natural cellulosic materials, such as cotton or cotton blends. These materials are immersed in a chemical bath, creating a permanent bond that allows the material to resist combustion. Treated fabrics have a greater potential for shrinkage because cotton fibers are hydrophilic and highly susceptible to dimensional changes when exposed to moisture and heat.
Inherently FR Fabrics
Inherently FR fabrics achieve protection because the chemical structure of the fiber itself is non-flammable. Materials like aramids, modacrylics, and PBI possess a molecular structure resistant to heat degradation. Since the flame-resistant properties are built into the fiber, they cannot be washed out. These thermally stable synthetic fibers are less prone to the swelling and relaxation that causes shrinkage in cotton, resulting in minimal dimensional change over the garment’s lifespan.
Primary Causes of Shrinkage in FR Garments
Shrinkage occurs when the tension applied to the fabric during manufacturing is released, allowing fibers to return to a relaxed state. Excessive heat is a primary catalyst, accelerating the relaxation of the yarn and the swelling of hydrophilic fibers like cotton. This heat is often introduced through high-temperature washing or aggressive drying cycles.
Mechanical agitation, such as harsh or prolonged washing cycles, also contributes significantly to size reduction. The friction and tumbling action cause individual fibers to compact and interlock more tightly. When agitation is combined with heat and moisture, the rate of dimensional change increases substantially.
Residual shrinkage is the small amount of size reduction that occurs even in properly manufactured garments. During the textile finishing process, fabric is stretched and dried under tension. Residual shrinkage is the amount the garment shrinks during the first few washes as the fibers relax from this induced tension.
Sizing and Acceptable Shrinkage Standards
Manufacturers design FR sizing to accommodate the small, expected dimensional change that occurs during the first few washes. Industry standards govern the acceptable limits of size reduction to ensure garments remain compliant and protective. For example, the National Fire Protection Association (NFPA) 2112 standard typically requires a garment to exhibit less than a three to five percent shrinkage rate after five cycles of washing and drying.
A three percent reduction in size means a 30-inch inseam could shorten by almost one full inch, impacting comfort and fit. Manufacturers use pre-shrunk or sanforized fabrics to minimize this initial relaxation. Garments that exceed the specified shrinkage allowance are considered non-compliant and compromise the wearer’s safety.
To measure excessive shrinkage, garment dimensions should be taken before and after the first few wash cycles. If the change exceeds the manufacturer’s stated tolerance or the industry standard of five percent, the garment may be defective or improperly cared for. This non-compliance directly impacts the protective coverage and fit required for safety.
Essential Care Instructions to Minimize Shrinkage
Controlling the laundering process is the most effective way to manage and minimize dimensional change in FR apparel.
Washing Guidelines
When washing FR clothing, selecting a cool or warm water temperature is preferable to hot water. Lower temperatures prevent the rapid fiber swelling and relaxation that causes size reduction. The use of soft water can also be beneficial, as hard water requires more detergent and can lead to harsher cleaning conditions.
Choosing the correct cleaning agent is important for maintaining size and flame resistance. Use non-aggressive, liquid laundry detergents. Strictly avoid the following:
- Fabric softeners, which can leave residues that interfere with flame-resistant properties.
- Starch.
- Chlorine bleach, which chemically damages the fabric structure and exacerbates shrinkage.
Drying and Agitation
The drying phase presents the greatest risk for heat-induced shrinkage. Tumble drying should be performed on a low heat setting or, ideally, on an air-dry cycle. High heat drying is the fastest way to induce excessive shrinkage, especially in cotton-based materials. Removing garments while slightly damp and hanging them to complete the drying process prevents overheating.
Proper loading of the washing machine also contributes to size stability by preventing excessive mechanical agitation. Overloading the machine causes garments to rub aggressively against each other, increasing the friction that compacts the fibers. Following these steps preserves the original dimensions of the garment.
How Shrinkage Affects FR Safety Performance
Excessive shrinkage directly compromises the garment’s ability to protect the wearer from thermal hazards. When an FR shirt or jacket shrinks, it pulls up at the wrist and torso, exposing skin in vulnerable areas. This loss of coverage means that during a flash fire event, the wearer’s wrists, midriff, or ankles may be left unprotected, leading to burn injuries.
Shrinkage also causes the garment to fit more tightly against the body. FR clothing is designed to maintain a small air gap between the fabric and the skin, which provides thermal insulation. This air gap slows the transfer of heat from the outer layer of the garment to the skin.
When the garment shrinks, this insulating air layer is compressed or eliminated as the fabric lies directly against the skin. Without the air gap, the heat transfer rate increases, raising the likelihood of second- and third-degree burns. Maintaining the garment’s original, relaxed fit is necessary to preserve its safety function.