Salt Mist
What is Salt Mist (Salt Spray) Testing?
Salt Mist (Salt Spray) testing is an accelerated corrosion test used to evaluate how materials and protective coatings perform in a highly corrosive salt fog environment. Samples are exposed inside a controlled chamber where a fine mist of saline solution (commonly NaCl) is continuously atomized at specified temperature and pH conditions.
Salt mist testing is widely used to assess corrosion resistance, coating quality, surface treatment performance, and comparative durability for metals, plated parts, painted/coated components, and assemblies.
What Salt Mist Testing Can Help You Solve
Corrosion resistance evaluation for metals, coatings, platings, and surface treatments
Coating / plating quality verification (process consistency and defect sensitivity)
Comparative benchmarking (supplier comparison, lot-to-lot, new vs legacy process)
Failure analysis support (early rusting, blistering, underfilm corrosion)
Design validation for environments involving marine exposure, road salt, or harsh humidity
QC screening and acceptance testing based on customer or industry specifications
Typical Applications
Automotive: fasteners, brackets, body hardware, plated parts, painted components
Electronics & enclosures: housings, frames, connectors (project-dependent)
Industrial hardware: clamps, hinges, springs, tools, structural parts
Surface engineering: electroplating, galvanizing, anodizing, conversion coatings, powder coating
Materials R&D: coating formulation and process optimization
Test Types & What You Receive
Common Test Modes (as requested)
Neutral Salt Spray (NSS): general corrosion resistance screening
Acetic Acid Salt Spray (AASS): increased severity for certain coatings
Copper-Accelerated Acetic Acid Salt Spray (CASS): high severity, often for decorative coatings
Cyclic / customized programs (optional): tailored exposure cycles when specified by customer requirements
Typical Evaluation Items
Time to first rust / white rust (as applicable)
Corrosion area estimation and progression tracking
Blistering, cracking, delamination, underfilm corrosion
Documentation with photos and inspection notes at defined intervals
Deliverables
Test conditions summary (program, concentration, temperature, duration)
Inspection records at agreed intervals
Photo documentation (before/during/after as applicable)
Final conclusion vs. your pass/fail criteria (if provided)
Sample Requirements
Sample types: coated or uncoated metal coupons, fasteners, plated parts, painted components, small assemblies
Quantity: enough for planned duration and any intermediate inspections
Preparation: clean and dry; avoid touching critical surfaces; label clearly
Masking / scribing: optional per spec (e.g., intentional scribe to evaluate underfilm corrosion)
Information to provide: material and coating system, thickness (if known), expected failure mode, applicable standard/spec, pass/fail criteria, inspection intervals
Workflow
Requirement review (standard, duration, pass/fail, scribe/masking, inspection frequency)
Sample receipt & documentation (photos, labeling, pre-check)
Chamber setup (solution preparation, temperature/pH verification, spray rate control)
Exposure & monitoring (scheduled inspections, records, photos)
Post-test evaluation (final inspection, optional cleaning protocol per spec)
Report issuance (conditions + results + photo evidence)
FAQs
What’s the difference between NSS, AASS, and CASS?
NSS is the most common baseline test. AASS increases severity using acetic acid. CASS further increases severity by adding copper ions and is typically used for certain decorative or high-demand coating systems.
Does salt mist testing predict real outdoor lifetime?
It provides accelerated, controlled comparison but does not perfectly replicate all real environments. It is best for screening and benchmarking coating systems and process consistency.
Should I request scribing?
If your standard requires it or you need to evaluate underfilm corrosion and coating adhesion robustness, scribing is recommended. For appearance-only coatings, non-scribed exposure may be preferred.
How are results evaluated?
Evaluation may include time to first corrosion, corrosion area, blistering, delamination, and photographic evidence—based on your chosen standard and acceptance criteria.
Can you test complex assemblies?
Often yes, as long as the assembly fits the chamber and safety requirements. Interpretation may be more complex due to crevices and mixed materials; providing intended service conditions helps.
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