Fastener Guide / Plating, Coatings & Finishes

Black Zinc

Black zinc is zinc plate with a black passivate. It looks like black oxide but gives far better corrosion resistance, especially with a sealer or topcoat.

Last reviewed 2026-09-10 · Governing standard: ASTM B633 (Type II or VI); ASTM F1941/F1941M-16(2025) · reference FG-10F119 · Report an error on this sheet

Black zinc vs black oxide

Black zincBlack oxide
BaseZinc plate + black passivateConverted iron oxide
CorrosionModerate (better with sealer)Low
Thickness5 - 12 micrometresAbout 1 micrometre
Hydrogen riskYes - electroplatedVery low

These tables carry the same figures as the printed sheet below.

The printed sheet

Black Zinc

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Text version of this sheet

Black zinc · black chromate or black trivalent

What it is

FIELD IDENTIFICATION

Black zinc is zinc plate with a black passivate. It looks like black oxide but gives far better corrosion

resistance, especially with a sealer or topcoat.

BLACK ZINC

Black passivate over zinc

Black zinc vs black oxide

Black zinc

Black oxide

Base

Zinc plate + black passivate

Converted iron oxide

Corrosion

Moderate (better with sealer)

Low

Thickness

5 - 12 micrometres

About 1 micrometre

Hydrogen risk

Yes - electroplated

Very low

Key points

Electroplating can load high-hardness steel with hydrogen. Parts at roughly HRC 39 and above (Grade 8, 10.9, 12.9, A574) need a qualified process and a

prompt embrittlement-relief bake, or a non-electrolytic coating instead.

Governing standards: ASTM B633 (Type II or VI); ASTM F1941/F1941M-16(2025). 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-10F119 · thefastenerapp.com/fastener-guide/plating-coatings-finishes/black-zinc · © The Fastener App. Reference only — verify the current governing standard, drawing and manufacturer data before specifying or installing.

Related sheets

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Share of the rep’s business

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Brunswick Galvanizing Inc.14.6%
Talleyrand Signs LLC8.0%
Mayport Tool & Die Inc.7.8%
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Premier Electric Group5.9%
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Coastal Maintenance Group3.3%
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CustomerHours a monthHours a week
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Mayport Tool & Die Inc.13.53.1
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Premier Electric Group10.22.4
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