| Etchant | Composition | Conc. | Conditions | Comments |
|---|---|---|---|---|
| ASTM No. 30 |
Ammonia Hydrogen Peroxide (3%) DI Water |
62.5 ml 125 ml 62.5 ml |
Mix Ammonia and water before adding peroxide. Must be used fresh. Swab 5-45 seconds | For etching copper, copper alloys and copper-silver alloys. |
| Adler Etchant |
Copper ammonium chloride Hydrochloric acid Ferric chloride, hydrated DI Water |
9 grams 150 ml 45 grams 75 ml |
Immersion is recommended for several seconds | For etching 300 series stainless steel and Hastelloy superalloys |
| Carpenters Stainless Steel Etch |
FeCl3 CuCl2 Hydrochloric acid Nitric acid Ethanol |
8.5 grams 2.4 grams 122 ml 6 ml 122 ml |
Immersion etching at 20 degrees Celsius | For etching duplex and 300 series stainless steels. |
| Kalling's No. 2 |
CuCl2 Hydrochloric acid Ethanol |
5 grams 100 ml 100 ml |
Immersion or swabbing etch at 20 degrees Celsius | For etching duplex and 400 series stainless steels and Ni-Cu alloys and superalloys. |
| Kellers Etch |
Distilled water Nitric acid Hydrochloric acid Hydrofluoric acid |
190 ml 5 ml 3 ml 2 ml |
10-30 second immersion. Use only fresh etchant | Excellent for aluminum and titanium alloys. |
| Klemm's Reagent |
Sodium thiosulfate solution Potassium metabisulfite |
250 ml Saturated 5 grams |
Etch for a few seconds to minutes | For etching alpha-beta brass, bonze, tin, cast iron phosphides, ferrite, martensite, retained austenite, zinc and steel temper embrittlement. |
| Kroll’s Reagent |
Distilled water Nitric acid Hydrofluoric acid |
92 ml 6 ml 2 ml |
Swab specimen up to 20 seconds |
Excellent for titanium and alloys. |
| Nital |
Ethanol Nitric acid |
100 ml 1-10 ml |
Immersion up to a few minutes. | Most common etchant for Fe, carbon and alloys steels and cast iron - Immerse sample up from seconds to minutes; Mn-Fe, MnNi, Mn-Cu, Mn-Co alloys. |
| Marble's Reagent |
CuSO4 Hydrochloric acid Water |
10 grams 50 ml 50 ml |
Immerse or swab for 5-60 seconds. |
For etching Ni, Ni-Cu and Ni-Fe alloys and superalloys. Add a few drops of H2SO4 to increase activity. |
| Murakami's |
K3Fe(CN)6 KOH Water |
10 grams 10 grams 100 ml |
Pre-mix KOH and water before adding K3Fe(CN)6 |
Cr and alloys (use fresh and immerse); iron and steels reveals carbides; Mo and alloys uses fresh and immerse; Ni-Cu alloys for alpha phases use at 75 Celcius; W and alloys use fresh and immerse; WC-Co and complex sintered carbides. |
| Picral |
Ethanol Picric acid |
100 ml 2-4 grams |
Seconds to minutes Do not let etchant crystallize or dry –explosive |
Recommended for microstructures containing ferrite, carbide, pearlite, martensite and bainite. Also useful for magnetic alloys, cast iron, high alloy stainless steels and magnesium. |
| Vilella’s Reagent |
Picric Acid Hydrochloric acid Ethanol |
1 gram 5 ml 100 ml |
Seconds to minutes | Good for ferrite-carbide structures (tempered martensite) in iron and steel |
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