The aim is to probe the mixed micellar compositions of three common industrial fluorotelomer surfactants used in fire-fighting foam formulations (Figure 1) using contrast variation SANS. These surfactants have already been studied individually (Figure 1) and now will be studied as mixed systems (2- and 3-component systems) over both a range of mole ratios and a range of typical compositions found in fire-fighting foam formulations. The data will allow us to understand how the surfactant aggregation is affected by mixing so as to provide new understanding on the colloidal properties of these practical surfactants. This is the second stage in a new 3-year program, including SANS, so that F-carbon surfactants can be replaced by more environmentally-responsive low-F or hydrocarbon analogues. Chris Hill is a 2nd year PhD student fully funded by fire-fighting technology company Angus Fire.