Salt spray test: assess the corrosion resistance of your materials
Salt spray testing is an accelerated aging method used to test the corrosion resistance of metallic or coated materials. It replicates, under controlled conditions, an aggressive saline atmosphere to predict the behavior of parts in demanding environments. This test is commonly used in the packaging, automotive, food processing, medical device, and industrial equipment sectors, where materials are subjected to severe atmospheric conditions.
To learn more about accelerated aging methods in the laboratory, you can consult our article: Accelerated aging test: a key method for assessing the durability of materials
What is the salt spray test?
Salt spray is a standardized corrosion test that involves exposing samples to a vapor-saturated environment of a saline solution (usually 5% NaCl) in a climate-controlled chamber. This chloride-rich atmosphere promotes the development of corrosion spots, allowing for the evaluation of the durability and performance of protective coatings , surface treatments, or bare materials.
This is a reference test in the context of quality control , validation of anti-corrosion coatings or conformity to the normative requirements of products placed on the market.
How does the salt spray test work?
The principle is based on the continuous generation of a salt mist projected into a test chamber, maintaining a constant temperature, generally around 35°C , and a relative humidity close to saturation . The samples are positioned in the chamber without contact with each other, at a defined angle.
Several types of tests exist, depending on the chemical and climatic conditions:
- NSS (Neutral Salt Spray) test : the most common, with a neutral NaCl solution.
- ASS (Acetic Salt Spray) test : enriched with acetic acid to simulate a more aggressive atmosphere.
- CASS (Copper-Accelerated Acetic Salt Spray) test : used especially for automotive parts and metallic decorative coatings.
Evaluation criteria include the appearance of corrosion (spots, pitting, filiform rust, blisters, etc.), peeling of the coating or alteration of appearance.
Technical characteristics of the salt spray test
- Standard test temperature : 35 ± 2°C
- Salt concentration : typically 5% NaCl, pH between 6.5 and 7.2
- Test duration : from a few hours to over 1000 hours depending on the standards
- Applicable standards :
- ISO 9227 (NSS, ASS, CASS)
- ASTM B117 (historical reference)
- DIN 50021 , NF EN ISO 60068-2-11 , MIL-STD-810
- Equipment : salt spray chambers with fine temperature and pressure control, sampling devices, continuous monitoring
For which matrices?
The salt spray test is applicable to many materials and finished products:
Main industrial applications
The BET method is essential in many industrial sectors where specific surface area determines product performance :
Léa Géréec
Technical and scientific expert
