  We study the spreading of viscous and viscoelastic drops on solid substrates
with different wettability. In the early stages of spreading, we find that the
viscoelastic drop spreads with faster and a different power law than the
Newtonian drop (i.e. aqueous glycerine solution) for the same zero shear rate
viscosity. We argue that the effect of viscoelasticity is only observable for
experimental time scales in the order of the internal relaxation time of the
polymer solution or longer times. Near the contact line, the effective
viscosity is lower for the viscoelastic drop than for the Newtonian drop.
Together with its shear rate dependency, this difference in effective viscosity
can explain the different spreading dynamics. We support our experimental
findings with a simple perturbation model that qualitatively agrees with our
findings.
