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, two times faster than the Caustic Etching Solution below. It contains no hydrofluoric acid.
- 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.
Caustic Etching Solution
- ASTM formula 177, a macro etchant for visual inspection of aluminum welds. It contains no hydrofluoric acid.
- ASTM formula 3, the most popular general-purpose micro etchant for aluminum alloys, shows microstructure and grains. It contains hydrofluoric acid.
- Special mixes for jet engine inspection/ repair.