  We study spinodal phase separation in unstable thin liquid films on
chemically disordered substrates via simulations of the thin-film equation. The
disorder is characterized by immobile patches of varying size and Hamaker
constant. The effect of disorder is pronounced in the early stages
(amplification of fluctuations), remains during the intermediate stages and
vanishes in the late stages (domain growth). These findings are in contrast to
the well-known effects of quenched disorder in usual phase-separation
processes, viz., the early stages remain undisturbed and domain growth is
slowed down in the asymptotic regime. We also address the inverse problem of
estimating disorder by thin-film experiments.
