Corrosion testing chemical treatment prior

In certain tests it is sometimes desirable to eliminate any effects of a mechanically achieved surface condition by chemical treatment or pickling of the surface prior to test. This may be done in a pickling solution alternatively, the test itself may be interrupted after sufficient corrosion has occurred to remove the original surface, the specimen then being cleaned and reweighed and the test started over again. Wesley found it to be desirable to pickle off about 0-008 mm from the surface of specimens in acid to improve the reproducibility of the tests. 

Sample Preparation For reproducibility reasons, it is important to consider a proper sample preparation, otherwise the resulting corrosion effect may be different from one exposure to the next. The test sample, usually a flatshaped pure metal, is commonly prepared before exposure through some mechanical or chemical treatment, such as abrasion with SiC paper, diamond polishing, or immersion in a mild acid, followed by rinsing with demineralized water and alcohol. Immediately after surface preparation, the metal forms an oxide or oxyhydroxide upon exposure to the ambient environment that usually possesses some corrosion protective properties. The properties of the oxide or oxyhydroxide film may age with time, which may alter its corrosion protective ability. Hence, it is important also to consider the storage time prior to exposure. 

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