Using supercritical carbon dioxide as a solvent for two novel flame retardants, chemists have made cotton as resistant to flames in lab-scale tests as Nomex, the popular material used in lab coats and NASCAR racing suits. Cotton is usually made flame resistant with resins that are applied to finished garments. But as these garments are laundered and go through normal wear and tear, the resin gradually comes off. Furthermore, the resins usually contain toxic halogenated compounds that are environmentally persistent. Aiming to make a more durable and environmentally benign flame retardant for cotton, Brian D. Condon, SeChin Chang, and coworkers at USDA’s Southern Regional Research Center, in New Orleans, wondered whether they could impart flame resistance to cotton fibers before they were made into fabric. The researchers reasoned that the size, shape, and nonpolar nature of CO2, a solvent that’s been used for dry cleaning, would easily allow it to penetrate cotton’s cellulose fibers and deliver two nonhalogenated piperazine-based flame retardants they had developed. Preliminary tests show that the treatment dramatically improves cotton’s resistance to flames. If the treatment proves to be durable, the process could be used to render anything made with cotton—such as clothing, bedding, and furniture—flame resistant.