OEM engineers, corrosion laboratories, coating-line quality teams and buyers specifying powder coating salt-spray evidence
Start with the product specification and decision
A salt-spray plan must state what decision the result supports: qualification, supplier comparison within an agreed program, process monitoring, failure investigation or batch acceptance. Define the substrate, pretreatment, powder or multilayer system, service risk and acceptance authority first. DAMEI supplies powder coating material; the applicator, customer and competent laboratory control the coated specimen, exposure and contractual decision.
Choose the current exposure practice without mixing methods
ASTM B117-26 specifies how to create and maintain a controlled salt-spray environment but does not prescribe a product specimen, exposure period or result interpretation. ISO 9227:2022 with its 2024 amendment covers NSS, AASS and CASS environments and likewise leaves specimen, duration and interpretation to the relevant product specification. Name the exact standard, edition and method; do not assume that different salt-fog or cyclic-corrosion methods are interchangeable.
Make the specimen represent the complete coating system
Record metal grade, fabrication, edges, welds, cleaning, pretreatment, primer and topcoat, powder batch, film build and actual part-metal cure. State whether specimens are production parts or panels and whether they are scribed, with the scribe method and location defined by the governing specification. Use sufficient replicates and controls because chamber, specimen and evaluation variability can affect results; a smooth panel does not automatically prove a complex production part.
Define exposure and handling before the chamber starts
The governing specification must set exposure duration, specimen orientation, interruptions, inspection points, allowed cleaning and post-exposure conditioning. The laboratory should document cabinet verification and specimen placement under the selected current method. Do not copy a generic hour target from another product, substrate or pretreatment, and do not change the test plan after seeing the result unless the deviation and approval are recorded.
Separate exposure conditions from evaluation and acceptance
The exposure practice creates the environment; the project must separately define what is evaluated and how. ASTM D1654-24 addresses evaluation of painted or coated specimens after corrosive exposure, including corrosion, blistering, adhesion loss at a scribe and other film failure. Record raw observations, photographs, locations and failure mode before applying the agreed rating and pass criterion. Rust, blistering, edge attack and scribe creepage are different outcomes and should not be collapsed into one vague pass statement.
Interpret hours as controlled evidence, not field-life warranty
ASTM B117 notes that stand-alone salt-spray results seldom correlate predictably with natural-environment performance, while ISO 9227 says its methods are not intended to predict long-term corrosion resistance. Compare only defined systems under the governing program and retain formulation, substrate, pretreatment, thickness, cure, laboratory, chamber, dates and acceptance decision. For an RFQ, send DAMEI the exact specification, drawing, exposure, layer system and required report rather than asking for an unsupported universal hour claim.
FAQ
How many salt-spray hours should powder coating pass?
There is no universal number. The governing product or customer specification must define the exact system, method, duration, evaluation and acceptance criterion. A value from another substrate, pretreatment or formulation is not transferable proof.
Does passing ASTM B117 predict outdoor service life?
No. ASTM B117 provides a controlled exposure environment and warns against stand-alone field-life correlation. Design, substrate, pretreatment, damage, climate, maintenance and other exposures also affect service performance.
Are ASTM B117 and ISO 9227 results interchangeable?
Do not assume so. Name the required standard, edition and ISO method, then follow the governing specimen, exposure and evaluation specification. Other continuous or cyclic corrosion methods answer differently defined programs.
What must a salt-spray report identify?
Identify the standard and edition, laboratory, specimen and replicates, substrate, pretreatment, coating layers, powder batch, film build, cure record, scribe, exposure, interruptions, evaluation method, photographs, observations, rating and acceptance decision.