Independence of Primary and Secondary Structures in Periodic Precipitation Patterns

Microscopic periodic precipitation patterns featuring both primary and secondary bands form in thin gel films. The initial conditions for the precipitation process are defined by wet stamping and are chosen such that the primary and secondary structures are not necessarily collinear; the fact that these structures propagate in different directions suggests that they form independently of one another. This hypothesis is further supported by a theoretical model in which two different intermediate species mediate band formation.