The present invention relates to a ceramic filter for molten metal filtration that comprises a bonded network of graphitized carbon and a method for producing such filters. In the method, one or more query related character patterns are defined. Electrical properties of the structure may be altered by applying energy to the structure, and thus information may be stored using the structure. The abrasive coating preferably consists essentially of 95% tungsten carbide and a binder of 5% cobalt and coats an amount of the inner surface in the range of 50% to 100%. A large chip pocket can also be provided.