Salt Fog (Spray) Corrosion Testing

Salt fog ( salt spray) testing is the most commonly used form of accelerated corrosion testing. It allows investigation and comparison of the corrosion resistance of different metals and the effectiveness of coatings and finishes. It is an inexpensive proven method, performed in a controlled environment, with repeatable results.


Salt fog corrosion testing allows a good evaluation of what can be expected before a new product or component is introduced to the market for usage. It can also be used to compare different coatings, materials or finishes, to determine which one is best for longer term service.

Testing is typically performed to ASTM B117 and several parameters can be evaluated. Some of these are as follows:

  • Relative amount of surface exhibiting corrosion (ASTM D610)
  • Relative amount of coating blistering (ASTM D714)
  • Effects on coating adhesion (ASTM D3359)
  • Time to white rust/red rust appearance (galvanized, galvalume, aluminized coatings)
  • Corrosion creep under coating, at scribe marks/scratches through coatings (ASTM D1654)

Our team at MTI can also perform forensic investigations to determine why your tested material may have not exhibited the expected corrosion resistance. This may include:

  • Chemical composition analysis of metal, substrate, or coatings
  • Obtaining thickness measurements of coatings
  • Investigation of the thickness and composition of multi-layered coatings
  • Verification of conversion coatings
  • Investigation of coating imperfections and adhesion before salt spray testing.

Photo at left shows a cast iron brake rotor with a black oxide coating before testing. Photo at right shows the rotor after 48 hours in the salt spray chamber.

MTi provides an easily understood report of test results, with tabulated data, interpretation of observations and findings, and photographic documentation, immediately upon completion of testing.


Failure Analysis Services

Determine cause of failure & recommend ways to prevent future recurrence.

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Corrosion Investigation

Determine cause of material degradation that reduces life expectancy.

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Verify fracture mechanism & initiation. Microstructure composition and imaging.

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Metallography Services

Reveals grain structure, thermo mechanical processing & flaw and defect characteristics.

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