The surface tension of proteins often exhibits a reproducible lagtime, which is sensitiv to a range of conditions such as concentration, pH, ionic strength. We have also found that the time behaviour of mixtures of proteins is quite different from that of the individual proteins. None of this is understood, although there are some theoreticl models available to be tested. We have an accepted experiment to probe the neutron reflectivity and surface tension simultaneously using the individual and mixed components of lysozyme and human serum albumin. Since making that proposal we have had the opportunity of testing out a perdeuterated protein, MPB, maltose binding protein, which has physical characteristics similar to those of HSA. The use of this protein on its own and in mixtures with lysozyme, would make the surface experiment very much more powerful and this is what we now propose.