Laboratory-scale HPLC purification presents many challenges to the chromatographer. One of the most frustrating challenges relates to the preparative column itself. Inconsistencies in column-to-column performance and lifetimes often result in lost samples, repeat purification runs, and poor scalability from small to large volume columns. Scientists at Waters recognized this problem and, over a 3-year period, studied all aspects of the packing processes as well as the column design. Launched in 2003, the Waters proprietary Optimum Bed Density (OBD) design is a direct result of these investigations.