ICDM has approved two methods for measuring the internal cleanliness of steel drums.
First, the Laboratory Method, based on a particulates counting and the NAS Standard. This method is expensive but gives a scientific measurement related to an International Standard, for customers having very high cleanliness requirement.
Second, the Factory method, is less precise but gives a good evaluation of the drum's cleanliness. Not only it is cheaper, but it can be done in production and is quite sufficient for most drums applications.