3.1 Rosin, particularly gum and wood rosin, occasionally contains small amounts of contamination such as sand, dirt or bark. Rosin derivatives occasionally contain traces of insoluble material as a result of the raw materials used in their production or they may be generated during the production process. In all instances the presence of such insoluble material should be minimal. This test method describes a rapid and reliable procedure for determining the amount of such insoluble matter. It is based on the knowledge that rosin and most of its derivatives are soluble in numerous organic solvents whereas most common contaminants are not. It is especially useful for internal quality control rather than sales specifications.