# Black Oxide

> Black with zero dimensional change: the gauge-and-tool finish for precision steel.

- Process group: Chemical Treatments
- HTML page: https://fabvector.com/finishes/black-oxide (Portuguese: https://fabvector.com/pt/finishes/black-oxide)

## Specifications

| Spec | Value |
|---|---|
| Coating thickness | 1–2 µm |
| Tolerance impact | Negligible (<2 µm) — a gauge pin measured before black oxide measures the same after. Safe on finished precision features without compensation. |
| Corrosion rating | 24–96 h salt spray with oil or wax seal — mild, indoor-grade protection only. |
| Appearance | Satin black with low glare; preserves the underlying machined texture. |
| Applicable substrates | steel, stainless-steel |

## Not suitable for

Bare outdoor or humid service — corrosion protection is very weak (24–96 h salt spray vs 96–200 h for chromated zinc); treat it as cosmetic-plus-oil only. Not applicable to aluminum or titanium; not a wear coating (the oxide is microns thin and offers no abrasion resistance).

## Typical applications

- Gauge pins, fixtures and inspection tooling
- Fasteners and dowel pins
- Optical mounts and glare-sensitive hardware
- Machine elements running in oil