Fabric that ignites slowly is slow to burn and, in some instances, may self-extinguish if the fire or flame is removed from it, is classified as fire-resistant or fire-retardant. The National Fire Protection Association has developed standards for this material that companies use when manufacturing the fabric and fire-resistant clothing. These fire-resistant properties can be retained throughout the life of a fire shirt if it is laundered correctly. Otherwise, the chemical treatment or even the fabric itself may deteriorate more rapidly, leaving the garment ineffective.

Things You'll Need:
Washing machine 
Laundry detergent without bleach or peroxide additive 

1. Turn the fire shirt garment inside out. This will protect the fabric surface and decrease the possibility of creating the fabric surface or streaking from abrasion caused by stiff, new fabric.
2. Use a laundry detergent that does not contain animal fats, hydrogen peroxide or bleach (both the chlorine and non-chlorine bleach that is in products such as Tide). These ingredients in laundry detergent will prematurely render the fire-retarding properties of a fire shirt ineffective. Carefully read the label of any laundry detergent to determine it does not contain harmful additives. Do not add fabric softener or starch, as that may mask, or coat, the fire-resistant properties on the fabric of your shirt, affecting its performance.
3. Wash your fire shirt in warm water that is no hotter than 140 degrees Fahrenheit. Some fire-resistant fabrics can tolerate temperatures up to 160 degrees Fahrenheit, but, to be safe, keep the water temperature at the lower level. Other, non-fire-resistant clothing can be washed with your fire shirt. Be sure you use an adequate water level when laundering your fire shirt.
4. Dry your fire shirt on the "Low" heat setting of your dryer. Remove your fire shirt promptly.