Salt Spray Testing

Operational Setup

Operation of the test chamber involves spraying a five percent sodium chloride solution at a controlled temperature of thirty-five degrees Celsius. The atomized solution creates a dense, corrosive fog that continuously coats the test specimens. The test is run for a specified duration, ranging from twenty-four to over one thousand hours, depending on the severity of the application.

Technicians inspect the parts at regular intervals to check for the first signs of corrosion, such as red or white rust. The angle at which the specimens are placed in the chamber is also standardized to ensure uniform exposure to the salt mist.

Material Limit

Correlation between the hours survived in the test chamber and the actual lifespan of the part in the field is limited because the chamber environment is constant and does not replicate the dry-wet cycles or ultraviolet exposure of the real world. Despite these differences, the test remains a valuable tool for comparing the quality of different coating batches. It provides a rapid way to detect defects in the plating process or paint adhesion.

Sourcing Metric

Quality engineers include salt spray testing requirements in purchase specifications for all metal fasteners and battery housing parts. Sourcing contracts define the minimum number of hours the parts must survive without showing rust. If a shipment fails to meet this requirement, it indicates that the supplier’s plating thickness or chemistry is deficient.

Buyers use these results to audit suppliers and ensure that only corrosion-resistant parts are used in vehicle assemblies.