In order to maintain their asymmetric lipid distribution, cellular membranes have a number of means to translocate lipid molecules across the bilayer. On top of the well-studied active flipping processes carried out by the flippases & floppases, there are also passive transfer mechanisms which facilitate the lipid migration even in protein-free bilayers. This process, is considered to be the significant natural process that cells must overcome in order to sustain 'normal' cell asymmetry. Despite this, the mechanism by which this occurs in a protein independent manner is poorly understood and warrants investigation.We aim to build selectively deuterated floating lipid bilayers on silicon with a buried iron layer, this will allow the system to be studied at two contrasts using polarised neutrons without the need to exchange the solvent, allowing us to observe the rate of lipid exchange.