Salt Spray Chambers are used to perform the Salt Spray Test also known as Fog Test. Salt Spray Test is an accelerated environmental corrosion test in which specimens/metals are exposed either continuously or intermittently to a fine mist of salt-water solution used to evaluate the corrosion resistance of paints, coatings, or electrical connections. Test duration depends on the corrosion resistance of the coating; the more corrosion resistant the coating is, the longer the period in testing without showing signs of corrosion. Or the Salt Spray test is a standardized test method used to check corrosion resistance of coated samples. Coating provides corrosion resistance to metallic parts made of steel, zamak or brass.
Conditions required for a salt spray test (These conditions are maintained constantly for the duration of the test).
- A 5% by weight salt water solution is atomized by compressed air into a spray (also known as a ‘fog’ or ‘mist’) which is directed into an enclosed test chamber, containing the samples to be tested. The samples are located beneath the atomized salt spray and therefore not directly impinged upon by it.
- The salt spray so created ‘falls-out’ on to the samples under test at a rate of 1.0 to 2.0ml/80cm²/hour. Generally, and unless otherwise stated, the pH of this fall-out shall be neutral and controlled to between pH 6.5 to 7.2.
- The salt spray atomization is continuous for the duration of the test. The test duration varies according to the type of test sample and its intended application, but is generally given in multiples of 24 hours.
- Generally, and unless otherwise stated, the test chamber temperature shall be controlled at 35 degree C, and the humidity shall be maintained at 95-100% Relative Humidity.
Advantages of Salt Spray Test
- Short test duration; the test duration is short compared to the natural environment, the cost is limited and a standardized material is required.
- Can examine big samples; in the salt spray test it is possible to examine quite big samples, depending on the size of the salt spray chamber. Some chambers are too big in sizes that even allow the testing of a vehicle.
- Simple to perform; a salt spray test is simple to perform and its results seem to be immediately understandable to everyone.
- Salt spray test not only tests the corrosion resistance of the base material but can also show the influence of surface preparation on the resistance of stainless steel to atmospheric corrosion.
- Salt spray test is multi-material and can also be a combined test of material and surface finish, due to the fact that roughness and wettability play a considerable role in the final result.