SERDP and ESTCP are testing a variety of alternative PFAS-free surfactants, including hydrocarbons, siloxanes, polymeric materials, nano encapsulated materials, and other ingredients. We investigate foam stability at the macro and micro scale. As we develop promising formulations, they are tested for pool fire extinguishment and burnback at the 28-square-foot or larger scale at one of the DoD test facilities. We also measure relevant physical properties of the formulations and perform assessments of preliminary life cycle.