Picral

General Purpose

Buy from PACE

Composition

4% Picric Acid in Ethanol

Method

Immersion

Time

5–60 s

Alternative Names

Reveals

Pearlite lamellar detail (carbide-step morphology); spheroidized carbides; tempered carbide distribution; cementite networks in hyper-eutectoid steels

Typical Results

The picric-acid etchant. Attacks cementite, not ferrite, resolving pearlite lamellae with high clarity and showing tempered-carbide distribution in quench-and-tempered steels. Does not reveal ferrite grain boundaries; pair with Nital when both phases are needed. Standard for spheroidized and over-aged steel structures.

Application Method

Method:Immersion

Typical Time:5–60 s

Preparation Notes

Mix 4 g picric acid with 100 ml ethanol. Warm slightly to dissolve. CAUTION: Picric acid is explosive when dry.

Application Notes

Immerse 5–60 s at room temperature. Rinse with ethanol then water. Dry promptly; never let picric solution dry on the sample.

Troubleshooting

PICRIC ACID: never allow the solution to dry. Dry picric crystals are shock-sensitive explosives. Keep at least 10% water above the solid at all times.

Storage Notes

Amber glass with water always above any settled solid. Inspect monthly for evaporation; add water as needed. EXPLOSIVE WHEN DRY.

Picral

Alternative Names

Tags