Glyceregia

Material Specific

Composition

15ml HCl, 10ml HNO₃, 10ml Glycerol

Mixed

Method

Swab

Time

10–60 s

Alternative Names

Reveals

Grain boundaries, carbides, sigma phase, and sensitization-induced ditches in austenitic stainless; grain structure and primary carbides in Inconel, Hastelloy, and other Ni-base superalloys

Typical Results

Glycerol-modified aqua regia, slower and more controllable than straight aqua regia. The standard general etchant for austenitic stainless steels (304, 316, 321), nickel-base superalloys (Inconel 600/625/718, Hastelloy), and used as part of the ASTM A262 Practice C double-etch sensitization test.

Application Method

Method:Swab

Typical Time:10–60 s

Preparation Notes

Mix 15ml HCl, 10ml HNO₃, and 10ml glycerol. Add acids to glycerol slowly. CAUTION: Exothermic reaction.

Application Notes

Swab 10–60 s; glycerol slows the reaction so dwell time is hand-controlled. Never immerse; heat builds locally. Rinse with water then ethanol. Use in fume hood.

Troubleshooting

Solution destabilizes within hours of mixing; visible NO2/Cl2 evolution is the warning sign. Prepare same-shift; discard at end of day. Never store overnight.

Storage Notes

DO NOT STORE. Mix immediately before use; discard same-shift. Aqua-regia chemistry generates chlorine gas during decomposition.

Glyceregia

Alternative Names

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