Recent studies on the spontaneous formation of undulatory patterns of precipitate concentration, such as Liesegang and related phenomena, have shown that these effects can be explained on the basis of a competitive particle growth mechanism as underlies Ostwald ripening. However these effects require an overall gradient or boundary perturbation to induce regular patterning on a scale greater than the interparticle spacing to override the single crystal-so called “greedy giant” instability. Here we show that by allowing for precipitate particle mediated reactions involving the solute species (from which the precipitate is constructed) a fastest growing mode of wave vectorkd, 0