Weld Inspection Etchants

Our macroetching solutions are formulated by metallurgists to reveal weld features, such as the nugget or heat affected zone. These chemicals allow the user to measure the penetration depth. They're effective, easy to use and can be stored.

Wet sand the cross-section before macroetching with at least 600 grit abrasive. Mirror polish the surface if possible. The finer the finish, the better the etching chemical will work, and the more detail you will see. Rinse and dry the surface then apply a proper etchant with cotton swabs. Let it stand for a few seconds to minutes. When the weld is visible, rinse it with water to stop the reaction.

If you need assistance with a special alloy, please send a small sample to us. We will recommend a suitable product based on the test result.

 etched mild steel weld  

For carbon steel welds:

• Nital etch, 5%: The traditional choice for carbon steel welds. Contains nitric acid. It's more effective than rust removal jelly.

Fry's reagent: (Optional 2nd stage) For low carbon mild steel welds. Use after Nital etch. It will stain the weld and make it easier to see. 

Ammonium persulfate solution: A water-based alternative to Nital. Very effective on mild steel welds, but the shelf life is short.

Pictures: A36 mild steel

For stainless steel welds:

Stainless steel weld etch: General purpose stainless steel etchant. Unlike Lepito's Etch or Aqua Regia, no mixing or heating required.

Pictures: 304, 308, 316, 409, 439, 2205 duplex, 17-7 PH

For aluminum welds:

Caustic etching solution: Reagent grade chemical, much stronger than household oven cleaners.

• AWS D1.2 Basic Etchant: Listed in AWS welding code. 2X faster than the Caustic etching solution.

Pictures: 3003, 5052, 5085, 5456, 6061, 6063


Keller's reagent: For advanced user only. Contains hydrofluoric acid!

For copper & brass welds:

Ferric chloride etchant: Macro etchant from ASTM standard.

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