The KPNOX CuSO₄ Copper Sulfate Test is designed to verify the effectiveness of stainless steel passivation treatments by detecting the presence of free iron contamination on stainless steel surfaces. Free iron particles are commonly transferred during fabrication, machining, grinding, or handling with carbon steel tools and components, potentially compromising the corrosion resistance of stainless steel.
The copper sulfate test is based on an oxidation-reduction reaction that causes dissolved copper ions to deposit on areas containing free iron contamination. This rapid stainless steel passivation verification method is widely used to evaluate surface cleanliness and determine whether additional passivation treatment may be required.
This test is recommended for:
- 200 and 300 series austenitic stainless steels,
- precipitation-hardened stainless steels,
- 400 series ferritic stainless steels containing a minimum of 16% chromium.
The copper sulfate test is generally not recommended for:
- martensitic 400 series stainless steels,
- ferritic stainless steels containing less than 16% chromium,
- laser-marked stainless steel surfaces,
as these conditions may produce false positive results.
KPNOX CuSO₄ is commonly used in:
- pharmaceutical stainless steel systems,
- food-grade equipment,
- sanitary process piping,
- industrial stainless steel fabrication,
- ASTM passivation validation programs.
Compatible with:
- ASTM A967
- ASTM A380
- ASTM B912
- ASTM F1089
- AMS 2700
✅ Detects free iron contamination
✅ Verifies stainless steel passivation effectiveness
✅ Supports ASTM passivation validation
✅ Rapid stainless steel surface inspection
✅ Ideal for pharmaceutical and sanitary applications
