A mathematical model of crust formation in bread baking is outlined, and used to explore the effect of the model parameters on crust thickness and density. Experimentation suggested that the interactions between model parameters were relatively weak, so it was possible to present the model results in terms of the percentage change in crust thickness from a 10% shift in each parameter. The results showed that crust thickness was particularly sensitive to the temperature at which bubbles collapsed and the dough's vapour pressure, but relatively insensitive to pre-oven dough conditions and dry crust properties. The overall mass in the crust showed similar dependencies, but with the addition that the thermal conductivity of the inner dough became significant. (c) 2005 Elsevier Ltd. All rights reserved.