Hexavalent-chrome-free
Conversion coatings
As industry moves away from hexavalent chromium under RoHS, ELV, and WEEE, we offer the modern, hexavalent-chrome-free trivalent alternatives: Iridite NCP for aluminium and SurTec 650 for zinc-plated steel. Compliant, high-performance finishing, matched to your material and specification. For stainless steel, see our citric passivation service.
- Substrates
- Aluminium, zinc-plated steel
- Standards
- MIL-DTL-5541
- Turnaround
- 3–5 working days
Iridite NCP: trivalent chromate conversion (aluminium)
A protective trivalent (hexavalent-chrome-free) conversion coating for aluminium that improves corrosion resistance while keeping electrical conductivity and giving a good base for paint or powder coat. For stainless steel passivation, see Passivation.
| Materials | Aluminium and aluminium alloys |
|---|---|
| Finish | Clear / iridescent · minimal added thickness |
| Key properties | Corrosion resistance with retained electrical conductivity; good paint/bond base |
| Standards | MIL-DTL-5541 Type II, Class 1A & Class 3, RoHS & REACH |
| Turnaround | Typically 3–5 working days |
| Typical uses | Aerospace, defence, electrical enclosures, precision engineering |
SurTec 650 / 650V: trivalent passivation (zinc-plated steel)
A high-performance trivalent (hexavalent-chrome-free) conversion coating that sharply increases the corrosion resistance of zinc-plated components. Widely specified for fasteners and hardware in automotive, electrical, and defence work.
| Materials | Zinc-plated steel |
|---|---|
| Finish | Clear · minimal added thickness |
| Standards | MIL-DTL-5541 Type II, Class 1A & Class 3, RoHS, REACH, ELV, WEEE |
| Turnaround | Typically 3–5 working days · express available |
| Typical uses | Automotive, electrical, defence, and general engineering fasteners & components |