Working in a petrochemical plant or a refinery when it is pouring rain is a miserable experience. The only thing standing between you and hypothermia is your FR (Flame Resistant) rain suit. These suits are highly engineered garments. The outside is usually coated with a Durable Water Repellent (DWR) finish to make water bead up and roll off, while the middle layer is a waterproof but breathable membrane that lets sweat vapor out. If a flash fire occurs, the outer shell is treated with a chemical fire retardant to self-extinguish.
But workers are destroying these $400 suits every single time they wash them, completely ruining both the waterproofing and the flame resistance, simply by using the wrong laundry soap.
The number one enemy of FR rain gear is standard, off-the-shelf laundry detergent. Most standard detergents contain harsh surfactants, optical brighteners, and enzymes. When you wash a rain suit in these chemicals, the surfactants are designed to strip away oils. They do a fantastic job of stripping the DWR coating right off the nylon shell. After one or two washes, the water stops beading up; it soaks into the fabric and the suit "wets out," becoming a heavy, leaky sponge that will freeze you on a cold tower.
Even more dangerous is the use of fabric softeners or dryer sheets. Fabric softeners work by coating fibers in a microscopic layer of waxy lubricant-usually derived from animal fats or synthetic silicones. When you put a rain suit in the wash with fabric softener, that waxy coating clogs the breathable membrane, trapping sweat inside the suit. But the real hazard is fire. If you coat an FR garment in a waxy, petroleum-based fabric softener, you have essentially wrapped yourself in a highly flammable candle. In a flash fire, that softener residue will ignite instantly, fueling the fire and causing severe burns before the FR chemicals even have a chance to react.
FR rain gear must only be washed in warm water using a specialized, residue-free technical wash designed for waterproof breathable fabrics. Never use bleach, never use fabric softener, and never dry clean it. Tumble dry on a very low, gentle heat. The mild heat actually helps to reactivate the remaining DWR coating on the shell. If the suit starts to wet out but the fabric is still in good shape, you can spray or wash in a specialized DWR restorative treatment to bring the waterproofing back to life without destroying the fire resistance.
