Metal Finishing Guide Book


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Page 422 of 843

The beauty of dyed anodized aluminum can be further enhanced by color buffing the work after it is sealed and dried, using a lime-type composition, preferably containing some wax. In addition to actually polishing the coating, this step removes any traces of the sealing smut. Irregular shaped parts, castings, etc. are best finished by brushing with a Tampico brush or by tumbling with sawdust or other suitable media. PRETREATMENT Cleaning Proper and thorough cleaning of the aluminum surface prior to anodizing is one of the most important steps in the finishing process. Improperly cleaned material accounts for more reruns and rejected parts than any other single factor. It is essential that all machining oils, greases, body oils, and other surface contaminants be removed prior to the continuation of the anodizing sequence. Both alkaline- and acid-based proprietary cleaners are available that will do an adequate job. If the oils or greases are specific in nature, some cleaners may need to be "customized" for adequate results. What is clean? Generally, we speak of a part being clean if it exhibits a "waterbreak-free" surface. This means that if the water rinses off of the metal surface in a continuous sheet, the work is considered to be clean. If, on the other hand, the water "beads" up or forms water breaks, the part still has foreign matter on the surface and continued cleaning is necessary. Once the part has been determined to be clean, subsequent finishing steps can proceed. 415

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