Etching

[ Order Form ] Specific Etchants ] Common Etchants [ Etchant Database CD ] Product Description ] [ Home ]

Etching is a process for revealing the structure of the material, common etching techniques include:

Chemical
Electrolytic
Thermal
Plasma
Molten salt
Magnetic

The two most common techniques are chemical and electrochemical etching. Chemical etching is typically a combination of either an acid or base with an oxidizing or reducing agent in a solute such as an alcohol. Electrochemical etching is a combination of chemical etching with an electrical voltage/current.

Return to top

Common Etchants

There are a number of more common etching solutions. Several of them are listed in the folowing table.

Etchant	Composition	Conc.	Conditions	Comments
Kalling's No. 1	Distilled water CuCl2 Hydrochloric acid Ethanol	33 ml 1.5 grams 33 ml 33 ml	Immersion etching at 20 degrees Celcius	For etching martensitic stainless steels. Martensite will be dark and the ferrite will be colored.
Kalling's No. 2	CuCl2 Hydrochloric acid Ethanol	5 grams 100 ml 100 ml	Immersion etching at 20 degrees Celcius	For etching duplex 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 alloys - immersion for 10-20 seconds ; titanium alloys immersion for 10-20 seconds.
Kroll’s Reagent	Distilled water Nitric acid Hydrofluoric acid	92 ml 6 ml 2 ml	15 seconds	Excellent for titanium and alloys. Swab specimen up to 20 seconds.
Nital	Ethanol Nitric acid	100 ml 1-10 ml	Seconds to 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 - immersion up to a few minutes.
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 and carbide.
Vilella’s Reagent	Glycerol Nitric acid Hydrochloric acid	45 ml 15 ml 30 ml	Seconds to minutes	Good for ferrite-carbide structures (tempered martensite) in iron and steel

Return to top

Etchant Database CD

For more specific etchants, PACE Technologies offers an CD etchant database containing over 2200 etchants.


Metallographic etchant and training CD

Etchant database search result		Metallographic training basics

Return to top

ETCHING PRODUCT DESCRIPTIONS

ETCHING / SPECIMEN PREPARATION
Description	Quantity	Catalog Number
Etchant / Specimen preparation CD	each	CD-ETCH

Return to top

Technical Information - Metallographic Etching

Metallographic Etching

Metallography Support

Etching