3% Nitric AcidNital 3%
3% Nital
General Purpose
Composition
3% Nitric Acid in Ethanol
3%
Method
Immersion
Time
5–20 s
Alternative Names
Tags
Reveals
Ferrite grain boundaries; pearlite; bainite; tempered martensite (moderate contrast)
Typical Results
Slightly more aggressive than 2% Nital. Preferred for tempered martensite, fine bainite, and medium-alloy quench-and-tempered steels (4140, 4340, 8620) where 2% under-etches.
Application Method
Method:Immersion
Typical Time:5–20 s
Preparation Notes
Mix 3 ml concentrated nitric acid (HNO₃) with 97 ml ethanol. Add acid to ethanol slowly with stirring.
Application Notes
Immerse 5–20 s at room temperature. Swab gently if attack is uneven. Rinse with ethanol, then water; air-dry.
Troubleshooting
Over-etch on low-C steels: drop back to 2%. Under-etch on hardened tool steels: switch to 5% or to Vilella's.
Storage Notes
Tightly capped amber glass at room temperature. Stable 3–6 months.
Alternative Etchants
- 2% Nital
- 5% Nital
- 4% Picral
Similar Etchants
- 2% Nital
- 5% Nital