Salt Spray Testing

Salt spray testing is a corrosion resistance test used to evaluate how metals, coatings, and surface finishes perform when exposed to a controlled salt fog environment. The test accelerates corrosion under laboratory conditions to assess how effectively a material or protective coating resists rust, oxidation, blistering, and surface degradation.

Salt spray testing is widely used across manufacturing and quality control processes to evaluate product durability before products enter the market. Industries such as automotive, electronics, hardware, marine equipment, appliances, and construction materials frequently apply salt spray testing to assess corrosion resistance under simulated harsh environments.

Because corrosion can directly affect product performance, safety, and product lifespan, salt spray testing helps manufacturers and buyers evaluate whether coatings and materials are suitable for expected operating conditions.

Why Salt Spray Testing Matters

Corrosion affects both product quality and long-term performance. Exposure to moisture, humidity, salt, industrial pollutants, and changing environmental conditions can gradually weaken metal parts and coatings.

Salt spray testing helps evaluate whether a product can maintain acceptable performance under corrosive conditions by supporting:

• Corrosion resistance evaluation
• Surface coating verification
• Supplier quality control
• Product durability assessment
• Material comparison and validation
• Compliance with customer specifications

Products designed for outdoor, industrial, marine, or high-humidity environments often require corrosion testing during product qualification or ongoing production quality monitoring.

Common examples include:

• Fasteners and metal hardware
• Automotive components
• Outdoor furniture and fencing
• Electronic enclosures and brackets
• Electroplated and powder-coated parts
• Marine equipment and accessories

How Salt Spray Testing Works

Salt spray testing is conducted inside a specialized corrosion chamber that continuously exposes test samples to a fine mist of salt solution under controlled environmental conditions.

The objective is to accelerate corrosion in a repeatable laboratory environment to evaluate coating performance and material durability.

A typical salt spray testing process includes:

1. Sample Preparation

Representative product samples or coated materials are selected for testing. Surface condition, coating thickness, and preparation methods are typically defined by customer specifications or testing standards.

2. Chamber Placement

Samples are positioned inside the chamber at a specified angle to ensure consistent salt fog exposure.

3. Salt Fog Exposure

The chamber sprays a controlled saline mist continuously over the samples. Conditions such as temperature, salt concentration, pH level, and spray rate are maintained according to the selected standard.

4. Corrosion Evaluation

After a predetermined exposure period, inspectors or laboratory personnel examine the sample for signs of:

• Rust formation
• Blistering
• Surface degradation
• Corrosion creep
• Coating failure

Results help determine how effectively the material or coating withstands corrosive exposure.

Salt spray test duration varies according to product requirements, coating systems, industry expectations, and customer specifications.

For a more detailed breakdown of salt spray test duration requirements by product category, see our guide to Salt Spray Test Requirements by Product Type and Industry.

ASTM B117 and Other Salt Spray Testing Standards

Salt spray testing follows internationally recognized procedures to ensure consistent and repeatable results.

ASTM B117

ASTM B117 is one of the most widely used salt spray testing standards globally. It defines testing procedures for neutral salt spray exposure, including:

• Salt solution preparation
• Chamber operating conditions
• Temperature requirements
• Spray collection rate
• Test specimen positioning

ASTM B117 defines the testing method itself and provides a standardized process for generating comparable corrosion data.

ISO 9227

ISO 9227 is widely used internationally, particularly within European and industrial supply chains.

The standard includes multiple corrosion testing methods, including:

• Neutral Salt Spray (NSS)
• Acetic Acid Salt Spray (AASS)
• Copper-Accelerated Acetic Acid Salt Spray (CASS)

These methods are commonly applied to plated metals, decorative coatings, automotive components, and industrial products.

JIS Z 2371

JIS Z 2371 is a Japanese salt spray testing standard commonly referenced in Japanese manufacturing and supply chains. It shares many similarities with ASTM B117 while supporting regional technical requirements.

Common Industries That Use Salt Spray Testing

Salt spray testing is widely used across industries where corrosion resistance directly influences product performance, reliability, and durability.

Automotive Industry

Automotive manufacturers use salt spray testing to assess the corrosion resistance of:

• Fasteners
• Brackets
• Body components
• Brake parts
• Underbody coatings
• Plated metal parts

This is particularly important for products exposed to moisture, road salt, and harsh environmental conditions.

Electronics and Appliances

Electronic products often contain coated metal housings, connectors, brackets, and structural components vulnerable to corrosion.

Salt spray testing helps evaluate protective finishes used in:

• Consumer electronics
• Industrial electronics
• Electrical enclosures
• Appliances

Hardware and Construction Products

Construction and hardware products frequently undergo salt spray testing to assess corrosion resistance for outdoor use.

Examples include:

• Hinges
• Locks
• Bolts and screws
• Fencing systems
• Architectural hardware

Marine and Outdoor Equipment

Marine products and outdoor equipment experience high exposure to moisture and salt-rich environments. Salt spray testing helps assess material suitability for long-term performance.

Limitations of Salt Spray Testing

Although salt spray testing is widely used, it does not fully replicate real-world environmental exposure.

The test accelerates corrosion under controlled laboratory conditions but cannot reproduce every variable found in actual service environments.

Salt spray testing generally does not account for:

• UV exposure
• Temperature cycling
• Mechanical wear
• Pollutants and chemicals
• Changing humidity conditions

For this reason, salt spray testing is commonly used as a comparative quality tool to evaluate coating systems and materials under consistent conditions.

It is particularly effective for comparing product performance across suppliers, coating methods, or manufacturing batches.

Salt Spray Testing in Quality Control and Compliance

Salt spray testing supports multiple stages of quality control and supplier management.

Supplier Qualification

Manufacturers and buyers use salt spray testing to verify that suppliers can consistently meet corrosion resistance expectations.

Product Development

Engineers compare coating systems and materials to determine which options deliver suitable durability performance.

Quality Assurance and Inspection

Salt spray testing may be included as part of:

• Product qualification programs
• Production quality control
• Third-party testing programs
• Pre-shipment inspection support

Regulatory and Customer Requirements

Salt spray testing is commonly referenced in:

• Product specifications
• Engineering drawings
• Customer requirements
• Industry standards

Some buyers also require corrosion performance evidence to support durability claims.

---

Salt spray testing requirements vary significantly depending on product type, coating system, customer specifications, and industry expectations. Understanding the correct testing scope helps support consistent quality control and long-term product performance.

ECQA provides flexible options for corrosion testing coordination and quality verification requirements. Testing scope can be aligned with applicable standards, customer specifications, or project-specific requirements.