The microfiltration of milk based products is used industrially as a partial sterilisation technique and to facilitate selective separation of components. This paper describes (i) an experimental apparatus, protocol and key results and (ii) the development of a mathematical model, describing the flux recovery occurring when a 2.0 mum sintered stainless steel flat-sheet membrane fouled with reconstituted whey protein concentrate (NATC) powder is cleaned using aqueous sodium hydroxide. The model describes the unsteady-state hydraulic resistance variation which occurs when surface and in-pore bound material undergoes morphological changes during caustic cleaning. The model relies on simultaneous removal and swelling processes occurring within the surface and in-pore deposits, respectively. The validity and applicability of the model is discussed, along with possible future modelling developments. (C) 2002 Elsevier Science Ltd. All rights reserved.