Rosco Flamex for Delicate Fabrics - 1 gallon. Flamex DF is a gentle solution that maintains the soft qualities of the fabric while still providing a safe and secure flame treatment. It works with most natural or synthetic fibers. One gallon will treat approximately 600 square feet of fabric. Rosco Flamex DF is premixed and does not require dilution. The method of application and the amount of Flamex required for treatment varies with the fabrics in use. In order to maintain the soft drape of the fabric, spray application in multiple light passes is recommended. Over saturating the fabric may cause it to stiffen or otherwise alter its hand. It is always best to treat a test sample to determine how the fabric will react.