The thickness of the layer left behind when gas displaces a temperature-dependent power law liquid from a tube, after a period of static cooling of the liquid to the tube wall, is evaluated in finite element simulations. On the basis of some 300 numerical simulations, the dimensionless layer thickness is correlated with dimensionless cooling time, Pearson number, Biot number and power law index in convenient formulae which will be of value in estimating the effects of a gas delay in gas assisted injection moulding. (c) 2005 Elsevier Ltd. All rights reserved.