The following information is supplied for technical support only.
MetPrep DO NOT supply etchants in any form.

MetPrep Ltd are delighted to be able to publish a range of standard etchants.

Our intention is to offer a more comprehensive range of preparation parameters that will enable you to improve your own preparation techniques.

We will also attempt to include any etchants that you would be happy to recommend. Please send the details to Metprep Ltd.

Where water is advised please note that this refers to distilled water in all cases.

Carbon Steels

Macro Etch spacer_10px 10% Nital
10ml Nitric Acid
90ml Methanol
spacer_10px Versatile macro etch for Iron & Steel. Carburized and Decarburized areas as well as segregation.
Micro Etch Nital – 1
10ml Nitric Acid
90-99ml Methanol
Most common etchant for Iron, Carbon and Alloy Steels & Cast Irons. Reveals alpha grain boundaries and constituents. The 2% solution is the most common. Use by immersion for up to 60 seconds or by swabbing. The 5-10% solution is used for high-alloy steels.
Micro Etch Picral
2-4g Picric Acid
100ml Ethanol
Generally used for Iron and heat treated Steels. Recommended for pearlite, marteniste and bainite structures. Use by immersion or swabbing.
Micro Etch Vilella’s Reagent
1g Picric Acid
5ml HCl
100ml Ethanol
General structure of low alloy steels. Reveals prior austenite grain boundaries and bainitic structures.

Stainless Steels

Macro Etch spacer_10px Marble’s Reagent
50ml HCl
25ml Saturated
aequous solution of Copper(II) Sulphate
spacer_10px Used for revealing general structure.
Micro Etch Acid Ferric Chloride
10 g Ferric Chloride
30 ml HCl
120 ml Water
Swab etch to reveal general microstructure.
Micro Etch Kallings Solution
2 g Cupric Chloride
40-80ml Methanol
40ml Water
40ml Hydrochloric Acid
Ferrite and Martensite are darkened. Austenite appears light and carbides are unaffected.
Micro Etch 45ml Glycerol
15ml Nitric Acid
30ml Hydrochloric Acid
For stainless steels with high Cr content. Also Cr-Ni Cast steels.

Tool Steels

Micro Etch spacer_10px Sodium Picrate
1g Sodium Picrate
100ml Water – use boiling
spacer_10px Iron Tungstide is quickly darkened, Iron-Tungsten Carbide is slowly darkened and cementite is unaffected.
Micro Etch Methanol Regia
5 ml Nitric Acid
10 ml HCl
100ml Methanol
General microstructure.

Titanium Alloys

Macro Etch spacer_10px 50ml HCl (1.19)
50ml Water
spacer_10px For differentiation of alpha and beta Titanium.
Macro Etch 30ml HCl (1.19)
10ml HF
10ml Nitric Acid
50ml Water
General purpose macro etch for all Titanium alloys.
Micro Etch Kroll’s Reagent
2ml HF
10ml Nitric Acid
88ml Water
Useful etchant for most Ti based materials, especially Ti-Al-V alloys.
Micro Etch 15ml Hydrogen Peroxide
10ml Aqueous solution of Potassium Hydroxide
80ml Water
Swab etch for Titanium, Ferro-Ti, Ti-Al-V-Sn alloys. Alpha Ti is attacked, beta Ti is left unchanged.

Copper Alloys

Macro Etch spacer_10px 50ml Nitric Acid (1.40)
50ml Water
spacer_10px Macro etch for most Copper and Brasses. For grains and cracks.
Micro Etch 5g Iron (III) Nitrate
25ml HCl
70ml Water
General purpose etchant that reveals grain boundaries. Use by immersion.

Aluminium Alloys

Macro Etch spacer_10px Mixed Acids
5ml HF
20ml Nitric Acid
20ml HCl
60ml Water
spacer_10px Useful macro etch for most Al based materials. Reveals grain size, rolling directions and welded joints. – De-smut in 35% Nitric Acid afterwards.
Micro Etch Keller’s Reagent
2.5 ml Nitric Acid
1.5 ml HCl
1 ml HF
95 ml Water
Most common etchant for Al & Al Alloys, except high Si alloys. Swab etch 10 – 20 seconds.

Nickel Alloys

 Macro Etch spacer_10px 10g Copper Sulphate
50ml HCl
50ml Ethanol
50ml Water
spacer_10px Versatile macro etch for Nickel & Nickel based Alloys. May reveal grain structure in Superalloys.
 Micro Etch Kalling’s
2g Copper Chloride
40ml HCl
40-80ml Ethanol
Useful etchant for superalloys and stainles steels as well as Ni-Cu alloys. Good for grain structure. Generally used as swab etch.

 Magnesium Alloys

Macro Etch spacer_10px Mixed Acids
5ml HF
20ml Nitric Acid
20ml HCl
60ml Water
spacer_10px Useful macro etch for most Mg based materials.
Micro Etch Acetic Picral
100g Picric Acid
200ml Methanol
800ml Acetic Acid
800 ml Water
For general structure, reveals grain boundaries and twins. – This solution must be allowed to age for 24 hours
Micro Etch Citric Acid
10g Citric Acid
90 ml Water
General structure.
Micro Etch Acetic Picral
2ml Nitric Acid
98ml Methanol
General structure, particularly good for Zr containing alloys.

Molybdemum & Tungsten

Micro Etch spacer_10px 36g Sodium Hydroxide
36g Potassium Ferricyanide
100ml Water
spacer_10px Immersion etch for 10secs.

Niobium/ Tantalum Alloys

Micro Etch spacer_10px 5ml HF
95ml Nitric Acid
spacer_10px Useful etch for Niobium.
Micro Etch 60 ml HF
20ml Nitric Acid
20ml Glycerol
General structure for Niobium.
 Micro Etch 50ml HF
10g Ammounium Fluoride
For Tantalum. A much shorted etching time is required when the reagent is hot.