The spontaneous formation of multilayer structures at interfaces from surfactant self-assembly is an important structural signature associated with a wide range of technological applications and biological function. This proposal is part of a new programme (EPSRC, EP/G065705) to characterise such structures and to determine the major factor with control their formation and kinetics. We have reported the formation of such surface structures for the anionic surfactant LAS with Ca2+ ions. The kinetics of formation and the ultimate structure formed depends upon when the Ca2+ is added. This is not the case for the single chain systems, SLES. We attribute this to slow association /dissociation kinetics in the Ca2+ induced LAS lamellar structures. We request here beam time on SANS2D to determine the differences in aggregate association / dissociation rates for LAS and SLES by stopped-flow.