ASTM F22 Water-Break Test

Scope

ASTM F22 is used to detect hydrophobic contamination on surfaces that must be clean before further processing or use. It applies to metals, glass, ceramics, and certain polymers. It identifies contaminants such as oils, greases, waxes, silicones, fingerprints, machining fluids, and mold-release agents that prevent uniform wetting with water.

The test is a simple go/no-go cleanliness assessment rather than a quantitative measurement. It is commonly used to verify the cleanliness of metal components, glass and optical surfaces, electronic assemblies, aerospace parts, precision-machined components, and surfaces prepared for welding, brazing, bonding, coating, or painting, where residual contamination can affect product performance and process reliability.

Applications

• Post-cleaning verification — confirming that a cleaning process — solvent degreasing, aqueous alkaline cleaning, vapor degreasing, or acid treatment — has successfully removed hydrophobic contamination before the part proceeds to the next operation
• Adhesive bonding preparation — verifying surface cleanliness immediately before primer application or adhesive bonding in structural, aerospace, and industrial assembly programs where bond integrity is safety-critical
• Painting and coating preparation — confirming that surfaces are free of hydrophobic films before primer, paint, powder coat, or conversion coating application, where contamination would cause adhesion failure, fisheye defects, or premature coating delamination
• Electroplating and anodizing preparation — verifying that substrate surfaces are clean before entering plating or anodizing baths, where oil contamination would cause skip plating, poor adhesion, or bath contamination
• Soldering and brazing — checking that surfaces to be joined are free of hydrophobic films that would prevent flux activity and solder wetting
• Process control and cleaning system qualification — monitoring the effectiveness of cleaning processes over time and validating new cleaning chemistries, temperatures, or cycle times against a defined cleanliness acceptance criterion
• Laboratory glassware verification — confirming that glassware used in analytical chemistry, biological assays, or surface science experiments is free of hydrophobic residues that would affect meniscus behavior, wetting, or adsorption

Benefits

• No instrumentation required — the test requires only a clean water source, making it executable at the point of cleaning without laboratory equipment, chemical reagents, or trained analysts
• Immediate result — the water-break or water-sheet response is observed in real time as water is applied to the surface, providing an instantaneous cleanliness indication without waiting for measurement or analysis
• Extremely sensitive to trace contamination — hydrophobic films at very low surface coverage — in some cases approaching a monolayer — are sufficient to produce a visible water-break response, making the test sensitive to contamination levels that many instrumental methods would miss or require special preparation to detect.
• Non-destructive and non-contaminating — the test leaves no residue, does not alter the surface, and does not require contact with reagents that could themselves introduce contamination.
• Applicable in-process and in the field — the test can be performed on assembled structures, large components, and production parts in place, not only on laboratory specimens