  The spreading of large viscous drops of density-matched suspensions of
non-Brownian spheres on a smooth solid surface is experimentally investigated
at the global drop scale. The focus is on dense suspensions with a solid volume
fraction equal to or greater than $40\%$ and for drops larger than the
capillary length, i.e. for which the spreading is governed by the balance of
gravitational and viscous forces. Our findings indicate that all liquids
exhibit a power law behaviour typical of gravity-driven dynamics, albeit with
an effective suspension viscosity that is smaller than the bulk value. When the
height of the drop is of the order of the particle size, the power law breaks
down as the particles freeze while the contact line continues to advance.
