Using Brownian dynamics simulations, we investigate continuum percolat
ion in a system of colloid particles aggregating due to depletion floc
culation. For all values of aggregating potential, there is a lower th
reshold volume fraction of colloid particles at which a percolating cl
uster appears. This threshold defines a percolation ''phase'' boundary
that crosses the phase boundary between the colloid fluid phase and c
olloid fluid+crystal coexistence. In the two-phase coexistence regime,
the lifetime of percolated clusters increases dramatically, and there
fore the percolation threshold may be related to a transient gel thres
hold reported from experiment. In the phase coexistence regime, there
is, evidence of aging due to the thermal restructuring of clusters, im
plying a finite lifetime for percolating structures. (C) 1998 American
Institute of Physics.