Stability of a Borax-Based Smolder Retardant Finish for Cotton Upholstery Fabrics

Abstract

The stability of a borax/phosphoric acid/resin smolder retardant on cotton fabric following continuous exposure to varying degrees of temperature and relative humidity for up to 100 days was examined. Specimens were assessed for boric acid active ingredient by chemical analysis, for smolder resistance by the UFAC procedure, and for morphologic changes by scanning electron microscopy. Prior to exposure of the specimens, the finish formed a non-uniform waxy film with short protrusions covering the superficial fibers. During exposure to low temperature and relative humidity for 100 days, there was a small loss of boric acid with no accompanying loss of smolder resistance or change in microscopic appearance. The more severe conditions of temperature and relative humidity led to greater boric acid losses. With one exception, the smolder resistance of all specimens was classified as UFAC class I (safe for use over polyurethane foam substrates). The original waxy film encapsulating the fibers of the finished specimens became lobular and crystalline during exposure to the more severe environmental conditions.