Our macro-etching acids are formulated by metallurgists to reveal the weld nugget during the weld penetration test. These chemicals are effective on stainless steel, mild steel, aluminum, etc. They are all pre-mixed, ready-to-use, and can be stored at room temperature up to a year.

A typical macroetching procedure of weldments looks like this: It usually starts with cut marks removal by utilizing different grit sizes of sandpapers from coarse to fine. We use 180 grit, 320 grit, and 600 grit for the sanding. The cross-sectional surface needs to have a uniform 600 grit finish before etching. Mirror-polish the surface if possible. The finer the finish, the better the etching chemical will work, and the more details you will see. Rinse and dry the surface then apply the 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.

Carbon Steel Welds:

  • Nital Etch, 5%: The traditional choice for carbon steel welds. AKA Nitol or Nytal. It contains nitric acid and is more effective than rust removal jelly.
  • Fry’s Reagent: (Optional 2nd stage) For highlighting mild steel welds. Use after Nital etch. It will stain the weld nugget, make the weld darker and easier to see.

Picture: A36 mild steel weld

Stainless Steel Welds:

  • Stainless Steel Weld Etch: Our general purpose stainless steel etchant. Unlike Lepito’s Etch or Aqua Regia, no mixing or heating required. Plus, it can be stored.

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

Aluminum Welds:

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

  • Keller’s Reagent: For advanced users only. It contains hydrofluoric acid! Please handle it with care.

Copper & Brass Welds:

Titanium Welds:

Inconel 625 Weld:

  • Sand the weld surface to a uniform 600 grit finish. Rinse and dry the surface quickly, then etch it immediately with our Adler’s Reagent without any delay. Otherwise, Inco 625 will react with air and passivate.

Picture: Inco 625 weld

These chemicals are also available in 500 ml size, see below.