The lowercase suffix is arguably the most important part of the specification. In DIN 50961, the post-treatment suffixes are:
| Designation Part | Meaning | | :--- | :--- | | | German Standard for Zinc Electroplating | | Fe | Base Metal: Steel/Iron | | Zn | Coating: Zinc | | 8 | Thickness: min. 8 µm | | b | Finish: Blue/Clear Chromate (Trivalent) | din 50961 fe zn 8b
Older "b" passivation contained Cr⁶⁺ (carcinogenic). Today, trivalent Cr blue passivation (RoHS-compliant) is the functional replacement, though exact color and performance may differ slightly. The lowercase suffix is arguably the most important
| Specification | Coating | Thickness | Corrosion Resistance | Best for | |---------------|---------|-----------|----------------------|-----------| | DIN 50961 Fe Zn 8c | Zn + yellow passivate | 8 µm | Moderate-high | Outdoor fasteners | | DIN 50961 Fe Zn 12d | Zn + olive drab | 12 µm | High | Military/agricultural | | DIN 50961 Fe Zn 8b + Sealer | Zn + blue + organic seal | 8 µm | Moderate (delays white rust) | Electronic enclosures | | ISO 2081 Fe/Zn 8b | Same as DIN (near equivalent) | 8 µm | Same | International trade | | DIN 50979 Fe/Zn 8b | Zn-alloy (e.g., Zn-Ni) + passivate | 8 µm | Very high | Brake components, fuel systems | Today, trivalent Cr blue passivation (RoHS-compliant) is the