Weld Inspection Etchants

Our weld inspection solutions are formulated by metallurgists to show weld nugget, heat affected zone, penetration depth, etc. These macro etching chemicals are very effective and easy to use. They can also be stored.

To macro etch (or acid etch) a weld joint, sand and polish the cross section with at least 600 grit abrasive using power tools. Mirror polish the surface if possible. The finer the polish, the better the etching chemical will work, and the more detail you will be able to see in the weld cross section. Rinse and dry the surface after polishing and then apply the proper etchant with cotton swabs. Let it stand for few seconds to minutes. When you can see the weld, rinse it with water to stop the reaction.

If you have problem etching a weld, 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. It's more effective than the rust removal jelly.

Fry's reagent: (Optional 2nd stage) for low carbon or mild steel welds. Use after Nital etch. It'll 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. 

Example: A36 mild steel

For stainless steel welds:

Stainless steel weld etch: An effective etchant for stainless steel welds.

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

For aluminum welds:

Caustic etching solution: Reagent grade chemical, 2X to 4X stronger than oven cleaners. Contains no hydrofluoric acid (HF).

Examples: 3003, 5052, 6061, 6063


For copper welds:

Copper etch: A general purpose copper etchant.

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