Trivalent vs Hexavalent Chromate
Hexavalent chromium (Cr VI) passivates were the traditional zinc topcoat. Cr VI is toxic and restricted by RoHS, ELV and REACH in many markets, so trivalent (Cr III) passivates have largely replaced it.
Comparison
| Hexavalent (Cr VI) | Trivalent (Cr III) | |
|---|---|---|
| B633 types | II (colored), III (clear) | V (colorless), VI (colored) |
| Self-healing | Yes - repairs small scratches | Limited; sealers help |
| Regulation | Restricted (RoHS, ELV, REACH) | Compliant |
| Corrosion | Good | Comparable with a sealer or topcoat |
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Trivalent vs hexavalent chromate
What it is
FIELD IDENTIFICATION
Hexavalent chromium (Cr VI) passivates were the traditional zinc topcoat. Cr VI is toxic and restricted
by RoHS, ELV and REACH in many markets, so trivalent (Cr III) passivates have largely replaced it.
HEX (CR VI)
TRI (CR III)
Hexavalent vs trivalent passivates
Comparison
Hexavalent (Cr VI)
Trivalent (Cr III)
B633 types
II (colored), III (clear)
V (colorless), VI (colored)
Self-healing
Yes - repairs small scratches
Limited; sealers help
Regulation
Restricted (RoHS, ELV, REACH)
Compliant
Corrosion
Good
Comparable with a sealer or topcoat
Key points
Specify the passivate explicitly on the drawing; "yellow zinc" alone does not tell a plater which chemistry to use.
Governing standards: ASTM B633; EU RoHS / ELV / REACH. Editions shown are the latest confirmed as of September 2026. The drawing and the governing standard always take
precedence over this sheet.
torquing any fastener. Verify the current governing standard, project documents, OEM requirements, size, thread, coating and lot certification. To the fullest extent permitted by law, The Fastener App disclaims liability
arising from reliance on this reference.
Fastener Guide reference FG-F8D07F · thefastenerapp.com/fastener-guide/plating-coatings-finishes/trivalent-vs-hexavalent-chromate · © The Fastener App. Reference only — verify the current governing standard, drawing and manufacturer data before specifying or installing.
