For many applications such as paints, foods and drug formulations, aggregation of colloidal particles is prevented by combining polymer and surfactant adsorption. Key to this stabilization is how such adsorbed layers react to compression. From a recent investigation into the adsorption of SDS into a PEO brush, we know that at high grafting/polymer densities, SDS is pushed out of the polymer layer. Compressing a polymer layer containing SDS would increase the polymer density and would, we believe, also expel the surfactant. Clearly this could have a big effect on how well the layer stabilizes particles. We have developed a surface force style apparatus that allows direct measurements of the structure of polymer layers under compression using neutron reflection. We propose to use this setup to investigate our hypothesis that surfactants can be pushed out of a polymer layer by compression.