Etching a stainless damascus steel knife (or any damascus) is not as complicated as many people tend to believe. It is a straightforward process, which is used to enhance the appearance of the blade and bring the inherent pattern, lying in wait within the steel, to life.
Please note the safety instructions and warnings for handling acid and wear protective gear. Neutralize the Damascus steel thoroughly after etching with bicarbonate soda to avoid further etching/corrosion.
In order to achieve a perfect etching result, the following steps should be followed.
Step 1: Sanding
Bring your damascus blade (hardened) to a 400, 600 or higher up to 1200 grit hand satin finish depending on your personal preference.
Pro Tip (Lourens Prinsloo): Do not buff the blade before etching! Buffing closes the pores in the metal, which will keep the acid from getting in contact with the steel, and you’ll end up with a dull or an uneven etch.Lourens Prinsloo (KGSA)
Step 2: Cleaning
To etch Damascus evenly, the blade should be perfectly clean of any residue or oils that could affect the acids’ ability to reach the steel with denatured alcohol/methylated spirits. Thoroughly wash your blade and pat it dry with a clean rag or kitchen paper.
While you can, avoid using solvents like acetone because they can leave residue behind that interferes with the etch, and wear gloves if you can as the oil on your skin can also cause uneven etching.
Step 3: Dilution / Acid Mix
If you’re using ferric acid (carbon steels), dilute it with distilled water until you have pretty close to a 50/50 ratio of acid to water. Know that water (from the tap or other sources) can have different PH levels that will affect your mix. My tap water is slightly basic with a PH of 8, so I tend to use a stronger acid to water mix to achieve the correct strength.
For Stainless steels that are corrosion resistant, Muriatic acid / Hydrochloric (HCL), Nitric, or Sulphuric acids are recommended. They need no dilution.
Pro Tip (Jack Connan): Hydrochloric Acid (HCL) is the preferred choice when etching high corrosion-resistant steels like stainless.Jack Connan (KGSA)
DANGER: If you do decide to dilute or mix acids, be very careful as it can cause a violent reaction and physical injury.
Step 4: Warming the acid
You can etch our steel with various acids (Ferric, Hydrochloric (HCL), Nitric, or Sulphuric acids). In order to achieve a good result, the acid should be heated in a water bath to 50°C.
DANGER: If you feel you need to warm your acid for use, the best method is to place your container of acid into a large bowl of warm water (double boiler). Never put acid in the microwave! I have seen some makers use a sous-vide setup to warm and maintain the temperature. Or simply leave in the sun for a bit.
Step 5: Submersion
Hang your damascus piece in the container of acid so that it hangs freely and doesn’t touch the sides or bottom of the container.
Stainless steels resist acid far more than carbon steel, so be prepared to dedicate some time to the etching process. Keep checking on your blade, until you achieve the depth of etch you are looking for.
To ensure that the acid penetrates, you can swish the piece back and forth in the acid, but brushing is the best way to be sure you get an even etch. Using an old toothbrush, softly brush the Damascus in the acid to help remove any residual oil or grease that you might have missed during cleaning, and to brush away the dissolving material as the acid does its job.
To achieve that beautiful chatoyance or 3D shimmering effect that gives damascus a mesmerizing quality in the light, it’s recommended that multiple (4 to 5 or more) shorter etches rather than simply leaving the blade in the acid for a single long etch.
Pro Tip (Stuart Smith): Let your piece remain in the acid for 5-8 minute cycles (5 times), washing with running water and rubbing it out briefly with very fine (maroon) scotchbrite or 0000 steel wool between cycles.
Shorter emersions create sharper edges on the borders of the steels, which helps to create that chatoyance effect we’re after.
Repeat until the depth of etch is to your liking. Multiple etches can also help eliminate uneven etches.Watch Stuarts Youtube Video
Step 6: Neutralization
Remove your Damascus piece from the acid and dip it into your baking/bicarbonate soda, bath for 5 minutes to neutralize the acid.
You can also use Windex for this step, but don’t try to spray your piece. Pour the Windex into a container deep enough that you can completely submerge your Damascus item.
After 5 minutes, clean your piece with alcohol and pat dry with a clean rag. You can repeat steps 5 and 6 for a deeper etch if you desire.
If you have masked part of your piece so that it doesn’t etch, and you want to do another round in the acid and baking soda, completely remove the mask, clean the blade, and then reapply your mask before the second etch.
Skipping this step is not advisable, even if your masking still looks good because the acid can penetrate the second time around and ruin your design.
Step 7: Polishing
With stainless Damascus, one of the layers within the steel isn’t affected by the etching, which is what gives stainless Damascus that unique texture when it’s finished. Use a fine finishing sandpaper (#1200 to #2000) to gently buff the top of that slightly raised steel, and the other steel will remain dark and unpolished, giving you a beautiful and dramatic contrast.
If you prefer, you can polish with a 2000 grit buffing compound and a soft wheel to brighten your Damascus piece, but you’ll lose some of that contrast between the steel layers. Play with both this technique and the sandpaper to see which you prefer.
- Carbon: Some makers like to soak finished pieces in fresh coffee (coffee etching) to get an even darker contrast. As the coffee is a mild acid at best, this step is purely cosmetic and produces a striking visual contrast, and it’s great to prepare your pieces for photos.
- Stainless: Darkening stainless damascus so that it’s gives a high contrast etch, is more difficult than with carbon steels. Once properly cleaned, use a mixture of distilled water, ferric chloride, and hydrogen peroxide. Remember the health warning above on mixing acids.
Pro Tip (Damien Krause): has used Cold Instant Coffee as a post-etch finish on stainless damascus, where he submerged the blade for 2 hours. This was in consultation with Mareko Maumasi of Maumasi Fire Arts USA who popularised coffee etches.Damien Krause