Burning Softly:A Study of the Effect of Fabric Softener on the Flame Resistance of Clothes

Friday, 13 February 2015
Exhibit Hall (San Jose Convention Center)
Nathan D. Wille, Parker, TX
The purpose of this project was to find if fabric softener made fabrics less flame resistant and if it could be restored.  For children’s’ flame resistant pajamas, there is no warning that fabric softeners will decrease flame resistance.  Research shows that fabric softeners decrease flame resistance. The flame resistance of a fabric can be increased in a variety of ways.  Most often, the fabric is treated with special flame resistant chemicals.  Synthetic fabrics, such as polyester, are naturally flame resistant.  These fabrics have a property called thermoplasticity, where the fabric naturally melts and shrinks when exposed to flame.  This prevents these fabrics from igniting and burning as easily as other fabrics.  Basic properties of a fabric, such as porosity, can also influence flame resistance.  Larger pores allow for oxygen to be more present in the fabric, making it more flammable. The hypothesis developed was: If different fabrics are washed continuously with detergent and fabric softener, then the flame resistance will decrease, and will decrease most in 100% cotton fabrics, but flame resistance will be able to be restored after one or more washings without fabric softeners. In this project, 4 flame resistant fabrics were tested by washing them in detergent and with fabric softener, putting aside 3 samples of each fabric after 0, 1, 3, 5, 10, and 15 washings.  The fabrics were washed with detergent to see if the flame resistance could be restored.  The fabrics, at each washing level, were tested by exposing them to a flame and measuring the burn duration and char length, the standard measurements of flame resistance. In order to measure burn duration and char length, each sample was hung on a ring stand and exposed to a flame.  The flame was removed and the data was measured and recorded.  An average was calculated for each washing interval, for char length and burn duration.  The results showed that 3 of 4 fabrics had a decreased flame resistance with increased washings with softener.  The 100% Polyester, 100% Cotton, and 88% Cotton 12% Nylon fabrics all showed significant decreases in flame resistance, with the 100% cotton showing the greatest decrease.   The fabric softener affected the flame resistance of these 3 fabrics.  However, the 48% Modacrylic, 48% Tencel, 4% Spandex  was not impacted by the softeners.  This is most likely due to the high flame resistance due to the presence of metal in the fabric fibers.  After washings with fabric softener, some samples were washed in only detergent to see if flame resistance could be restored.  It was found that in all the fabrics with decreases in flame resistance, washings with detergent only restored the flame resistance to the original level.  This proves the fabric softener does not chemically react with the fabric, it only coats the fabric fibers.  After collecting and analyzing the data, the hypothesis was proven correct.  The flame resistance decreased after fabric softener washings and decreased most in the 100% cotton.  Flame resistance was restored after washing with detergent only.