ASTM E407 No. 3
ASTM No. 3
General Purpose
Composition
100ml Ethanol, 5ml HNO₃
5%
Method
Immersion
Time
15s
Alternative Names
Tags
Reveals
Grain boundaries, ferrite, pearlite
Typical Results
ASTM standard etchant. Similar to 5% Nital. Good for carbon and low-alloy steels.
Color Effects
Pearlite darkens, ferrite remains light
Compatible Materials
Incompatible Materials
Application Method
Method:immersion
Typical Time:15 seconds
Preparation Notes
Mix 5ml concentrated nitric acid (HNO₃) with 100ml ethanol. Add acid to ethanol slowly with stirring.
Application Notes
Immerse sample for 15-30 seconds. Rinse with ethanol then water. Dry with compressed air.
Troubleshooting
Similar to 5% Nital. If over-etched, reduce time. If under-etched, increase time slightly.
Storage Notes
Store in dark glass bottle with tight cap. Keep away from light. Shelf life: 3-6 months if properly stored.
Alternative Etchants
- 5% Nital
- 3% Nital
Similar Etchants
- 5% Nital
- 3% Nital