Analysis of multiple front formation in the wetting of thin-layer plates

Multiple fronts were formed when pure liquids such as methanol or heptane and multi-component liquids such as ethanol-toluene mixtures were flowed through initially dry thin-layer chromatography plates, whether the stationary phase was naked silica or octadecyl-silica. A minor modification to a commercially available thin-layer chromatograph allowed the fronts to be clearly seen, and their dynamics to be measured experimentally. A model is proposed to explain their formation and motion.