What Is the Correct Procedure for a Salt Spray Test?

[prestogroup]

A Salt Spray Test (SST) is a corrosion testing method used to evaluate the resistance of metals, coatings, and surface treatments to a controlled salt-laden environment. It helps manufacturers assess coating quality, identify corrosion defects, and compare the corrosion resistance of different materials.

Salt Spray Test Procedure​

The test is generally conducted according to standards such as ASTM B117 or ISO 9227. The basic procedure involves the following steps:

1. Prepare the test samples: Clean the samples according to the applicable test standard without damaging the protective coating or surface.
2. Prepare the salt solution: Dissolve high-purity sodium chloride (NaCl) in distilled or deionized water to achieve the specified concentration.
3. Set up the chamber: Fill the salt spray chamber with the prepared solution and verify that the temperature and spray conditions meet the required standard.
4. Position the specimens: Place the samples inside the chamber at the specified angle, ensuring that they do not touch each other or allow solution to drip from one specimen onto another.
5. Start the test: Generate a continuous salt mist under controlled conditions for the specified test duration.
6. Inspect the samples: After testing, evaluate the specimens for rust, blistering, coating damage, or other signs of corrosion, following the relevant assessment criteria.

Recommended Chamber Temperature and Salt Solution Concentration​

For a standard neutral salt spray test under ASTM B117 or ISO 9227 NSS conditions, the commonly specified parameters are:

• Chamber temperature: 35°C ± 2°C
• Salt solution concentration: 5% sodium chloride by mass, approximately 50 g of NaCl per liter of water as a practical preparation guideline
• Salt solution pH: Typically 6.5–7.2
• Test duration: Determined by the applicable product specification or testing requirement

These apply conditions to the neutral salt spray (NSS) method. Acetic acid salt spray (AASS) and copper-accelerated acetic acid salt spray (CASS) tests use different solution chemistry and may require different conditions.

Importance of Using a Salt Spray Chamber​

Maintaining consistent temperature, salt concentration, pH, and spray conditions is essential for obtaining repeatable test results. A Salt Spray Chamber helps manufacturers assess the corrosion resistance of automotive components, metal coatings, fasteners, electrical components, and other industrial products.

Presto Stantest Pvt. Ltd. offers salt spray testing instruments designed to support corrosion testing and quality control. Selecting a suitable chamber and following the relevant testing standard helps manufacturers evaluate protective coatings and maintain product quality.

Note: Always verify the latest applicable version of ASTM B117, ISO 9227, or the customer's product specification before conducting the test. Salt spray results should not be used alone to predict the service life of a product in real-world conditions.