ASTM No. 1

General Purpose

Composition

100ml Ethanol, 1-5ml HNO₃

1-5%

Method

Immersion

Time

10s

Alternative Names

Reveals

Grain boundaries, ferrite, pearlite

Typical Results

ASTM standard general-purpose etchant. Similar to Nital but with variable concentration. Good for carbon and low-alloy steels.

Color Effects

Pearlite darkens, ferrite remains light

Compatible Materials

Incompatible Materials

Application Method

Method:immersion

Typical Time:10 seconds

Preparation Notes

Mix 1-5ml concentrated nitric acid (HNO₃) with 100ml ethanol. Adjust concentration based on material hardness. Add acid to ethanol slowly with stirring.

Application Notes

Immerse sample for 10-30 seconds. Adjust time based on concentration used. Rinse with ethanol then water. Dry with compressed air.

Troubleshooting

Start with lower concentration (1-2%) for softer steels. Increase concentration for harder materials. If over-etched, reduce concentration or time.

Storage Notes

Store in dark glass bottle with tight cap. Keep away from light. Shelf life: 3-6 months if properly stored.