There appear to be as many methods for separating solids from liquids as there are slurry streams to treat. Many of these methods involve the use of the filtration process. Filtration generally has one of two objectives; remove as much liquid from the solid phase as possible or remove as much solid from the liquid phase. Whilst these objectives sound the same the distinction is significant and generally relates to which of the two streams (solids or liquids) contains the material of value. Knowing this objective is just the first step in setting up and performing filtration testwork. Many other factors need to be understood if your filtration tests are ultimately going to lead to the installation of the correct filter type and size. To help you along the way, three DOs and a DON’T for filtration testwork are outlined by Tim Kram in Outokumpu's electoronic newsletter Output (Issue 4, December 2002).