Salt spray test or fog spray test is incorporated in many industries to estimate the corrosion resistance of the coating. It is an accelerated test to simulate the environmental conditions in a controlled manner. The specimens are exposed to spray or fog of salty water. This helps in estimating the behaviour of the coating in real working conditions. The period of test depends on the coating. For a good coating, the duration of the test is extended. The test procedure is defined by the relative testing authorities and it is a standardised test process to assess the corrosion resistance of the materials. The metal parts are usually coated by different processes to ensure protection from environmental conditions and oxidation.


Uniform conditions are needed to be maintained throughout the test cycle. A salt spray chamber is designed in a way to achieve accelerated environmental conditions for longer run.

  • An NaCl solution is used to create the salty fog with 5% salt by weight. This is atomised with the compressed air to form a spray. To spread this, fog is spread uniformly throughout the chamber. The chamber is very well insulated with glass wool to retain the conditions inside it.
  • The salty fog is sprayed on the test sample. The pH level of the salt is to be maintained at the value of 6.5 to 7. The spray is made to fall at the rate of 1.0 to 2.0ml/80cm²/hour. This is a standardised rate to determine the accurate behaviour.
  • The test period is defined as 24 hours, 48 hours or 72 hours, i.e. in the multiple of 24. Also, the test duration highly depends on the intended application. The spray should remain continuous throughout the test. For that matter, external reservoirs are provided.
  • The temperature of internal chamber need to be maintained at 37°C with relative humidity of 95%. This can be varied, if and only if testing standards allow to do so.

Benefits of Using Fog Spray Chamber

  • It is an accelerated test. How your product going to behave over the years can be determined in some hours.
  • Huge customization options are available. From testing of fasteners in a 250 ltrs chamber to walk in chambers, it can be modified as per the industrial requirement and scope of the machine.
  • Visual observations can declare the sample as pass or fail. No complex calculations or derivations are required.
  • It is widely used to test the behaviour of the coating and surface beneath it. Coated and uncoated samples can be easily tested.

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