Just before setting crystallization experiments, one may choose to centrifuge or filter the sample to remove amorphous material, particulates, and aggregates, or not. One school of thought says that during initial screening, one should not centrifuge or filter the sample before the setup, as particulates and amorphous material may serve as a nucleating agent for crystallization. This school then suggest during optimization that the sample then be centrifuged or filtered to improve crystal quality. The OCD school of thought says be consistent, be clean, and always filter (0.22 micron) or centrifuge the sample. Centrifugation may be preferable to filtering, as there is no risk of sample loss due to the macromolecule binding to a filter, or dead volume, both wasting precious protein.