Correct Preparation of Salt Solutions for Salt Spray Testing

Salt spray testing is a critical corrosion evaluation method widely used in industries such as automotive, aerospace, and electronics. To ensure accurate and repeatable test results, it is essential to prepare the salt solution correctly and use a high-quality salt spray test chamber that maintains precise testing conditions. Below are the preparation procedures for common salt spray tests, including Neutral Salt Spray (NSS), Acetic Acid Salt Spray (AASS), and Copper-Accelerated Acetic Acid Salt Spray (CASS):

1. Neutral Salt Spray (NSS) Solution Preparation

1. Prepare sodium chloride solution: Dissolve 50g of sodium chloride (NaCl) in 1L of distilled or deionized water to achieve a concentration of 50g/L ± 5g/L. Stir until completely dissolved.
2. Adjust pH (if necessary): Measure the pH of the solution using a pH meter. The pH should be within 6.4–7.0. If adjustment is required:

• • Use sodium hydroxide (NaOH) to increase pH.
  • Use glacial acetic acid (CH₃COOH) to decrease pH.
  • Note: Even small amounts of NaOH or acetic acid can significantly alter pH, so add cautiously.

For optimal performance, ensure the solution is used in a professional salt spray test chamber that provides consistent temperature, humidity, and spray distribution.

2. Acetic Acid Salt Spray (AASS) Solution Preparation

1. Prepare base sodium chloride solution: Same as NSS (50g NaCl per 1L distilled/deionized water).
2. Adjust pH: Add glacial acetic acid to the NaCl solution while stirring. Measure the pH until it reaches 3.0–3.1.

A reliable salt spray corrosion test chamber with precise pH monitoring and spray control is crucial for AASS testing, as slight deviations can affect test validity.

3. Copper-Accelerated Acetic Acid Salt Spray (CASS) Solution Preparation

1. Prepare sodium chloride solution: Same as NSS (50g NaCl per 1L distilled/deionized water).
2. Add copper(II) chloride (CuCl₂):
3. Dissolve 0.26g/L ± 0.02g/L of CuCl₂·2H₂O (or 0.205g/L ± 0.015g/L anhydrous CuCl₂) in the NaCl solution.

Adjust pH: Add glacial acetic acid while stirring until the pH reaches 3.0–3.1.

CASS testing requires an advanced salt spray test chamber capable of maintaining strict temperature and corrosion acceleration conditions to ensure fast and accurate results.

4. Key Considerations for Salt Spray Testing

Purity requirements:

Use high-purity NaCl (≥99.5%) with ≤0.1% sodium iodide and ≤0.5% total impurities.

Avoid NaCl with anti-caking agents, as they may act as corrosion inhibitors and affect test results.

Filtration: Filter the solution before use to prevent nozzle clogging in the salt spray test chamber.

Pre-test checks:

Verify the salt concentration and solution level before each test.

Ensure the salt spray corrosion test chamber is properly calibrated for temperature, humidity, and spray uniformity.

Why Choose a Professional Salt Spray Test Chamber?

A high-performance salt spray test chamber ensures:

✔ Precise environmental control – Maintains stable temperature, humidity, and spray conditions.

✔ Corrosion resistance – Made of high-quality PP or PVC materials to withstand long-term testing.

✔ Compliance with standards – Meets ASTM B117, ISO 9227, and other industry requirements.

✔ User-friendly operation – Automated controls for consistent and repeatable test results.

For industries requiring reliable corrosion testing, investing in a high-quality salt spray test chamber is essential to achieve accurate and repeatable results.