Particular embodiments of the present invention include a progressive sipe mold member with an undulation on its upper member and a corresponding sipe formed within a tire tread. In a particular embodiment, the present invention includes a progressive sipe mold member for use in a mold, the mold member comprising: an upper mold member extending downwardly from a top end to a bottom end with an undulation therebetween; and, a first lower projection member and a second lower projection member, each lower member extending downward from the upper mold member. The sipe mold member may also have a sweep axis along which the sipe mold member undulates in a desired path. Also, the lower projections may have scallops or recesses along their outward and inward facing surfaces. The mold member creates a sipe in the tread of a tire that has the negative image of the shape of the mold member.