Physical developer (PD) is a latent fingerprint development technique that is highly effective on paper and related surfaces, notably banknotes. The process exploits a redox reaction in which Ag(I) ions in solution are reduced by Fe(II), resulting in deposition of metallic silver on fingerprint residue on the surface. The standard formulation includes both a cationic and non-ionic surfactant, whose presence is critical to formulation stability and efficacy, but whose role is poorly understood. However, the surfactant adsorption can be expected to play a significant role. Here, we seek to extend our study from a successful initial experiment studying the cationic surfactant alone to understand the competitive nature of adsorption between the two surfactants on a silver surface using specular neutron reflectivity. The outcomes will guide optimization of the PD and derivative process.