In multiple developments, the layer is developed for some chosen distance, then either the layer or the mobile phase is with drawn from the developing chamber, and adsorbed solvent evaporated from the layer before repeating the development process. This is a versatile strategy for separating complex mixtures since the development distance, time for development (if continuous development is used), and composition of the mobile phase, can be changed for each development, and the number of developments optimized to obtain the desired separation. Multiple development techniques facilitate the use of step wise solvent gradients, which are more common in thin-layer chromatography than continuous solvent gradients of the type used in column liquid chromatography. As a result of the zone refocusing mechanism and more optimum use of solvent selectivity, multiple development results in higher resolution for mixtures of a wide polarity and improved detect ability for sample components because the separated zones are usually more compact.