The aim is to understand how the addition of a common hydrogenated/ deuterated oil affects the size of the self-assembled structure of three common industrial fluorocarbon (FC) surfactants used in fire-fighting foam formulations (Figure 1) using contrast variation SANS. These surfactants have already been studied individually by SANS and now will be studied in the presence of different concentrations of oil (cyclohexane), over both a range of surfactant concentrations which are commensurate with commercial fire-fighting foam formulations. Fire-fighting foams are generally employed on liquid fuel fires, therefore the degree of emulsification is of great interest to understand (as this can have adverse effects of foam stability (Figure 1)) and this experiments represents a model system close to practical application conditions in which we can study this effect.