Aluminum Etchants

2% HF (Alpha Case)

ASTM formula 11, attacks FeAl3, other constituents outlined. It contains hydrofluoric acid as the name implies.

AWS D1.2 Basic Etchant

A macro etchant for visual inspection of aluminum, listed in AWS welding code D1.2. It does NOT contain hydrofluoric acid.

Barker’s Reagent

ASTM formula 5, an electrolyte for electrolytic etching pure aluminum, 1000, 3000, 5000, 6000 and 7000 series. Need a polarized light microscope to see the result.

Keller’s Reagent

ASTM formula 3, the most popular general-purpose micro etchant for aluminum alloys, shows microstructure and grains. It contains hydrofluoric acid.