Rheological measurements on materials with fibre-like inhomogeneities will be significantly affected by sample size when the in-plane dimensions of the sample are comparable with the length of the fibres. In this paper a 3 10 t hydraulic press has been modified for squeeze flow rheology studies so that large tools that will minimize the influence of sample size can be used in combination with high closing velocities. Isothermal squeeze flow rheology experiments of GMT have been performed for closing velocities up to 30 mm/s corresponding to maximum closing forces of 1000 kN. Successful power law fits of closing velocity versus closing force have been performed for the velocity interval. Four different analytical models have been fitted to the experimental data and the accuracy in these has been investigated. The force prediction of the biaxial extension model is acceptable for the major part of mould closure, but better fits during the last part of mould closure were obtained using an additive model incorporating both shear and extensional flow.