Copperhead San Mai

Step 1: Sanding

Bring your Damascus to a 400 to 600 grit finish. If you’re using muriatic acid, you can bring the Damascus up to 1200 grit, or you can leave it at 400 grit. Either is effective however the color contrast is darker with Ferric Chloride For ferric acid, keep the grit between 400 and 600. Do not buff before etching. Buffing closes the pores in the metal, which will keep the acid from absorbing, and you’ll end up with an uneven etch.

Step 2: Washing

To etch Damascus, it should be perfectly clean. Thoroughly wash your piece with pure alcohol or brake cleaner and pat it dry with a clean rag.

Step 3: Dilution

If you’re using ferric acid, dilute it with Distilled water to a 10% Ferric, 90% Distilled water ratio. Never use tap water, spring water, or filtered water – they will all cause problems with the etc. Be sure that your distilled water hasn’t been sitting for more than a year. Muriatic acid needs no dilution.

Step 4: Warming the Acid

For both muriatic acid and ferric chloride, the temperature should be between 70 and 100 degrees Fahrenheit, about room temperature. If 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. **Never put acid in the microwave**

Step 5: Submersion Etching

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. Leave submerged for 60 seconds then pull the damascus out of the etchant and brush the entire surface of the damascus with a soft bristle toothbrush, this will help remove any residual oil or grease that you might have missed during cleaning, and help to brush away the dissolving material as the acid does its job. After brushing submerge the damascus back into the etchant and leave it submerged for 15 minutes.

Step 6: Neutralization

Remove your Damascus piece from the acid and submerge it into your baking soda bath for 5 minutes to neutralize the acid. Pat dry. After neutralizing, spray damascus with WD-40 and hang for 3-5 hours which can darken the color contrast.

 ***You can repeat steps 5 for a deeper etch if you desire***

Coating: ATP-641, Turco, or similar high temperature anti-scale/decarburization coatings can be used in replace of foil to reduce scale or surface decarburization.

Preheating: Heat oven to 1300°F and place material in oven.

Austenitizing (High Heat): Heat slowly (400°F a/hr) from the preheat to 1475-1500°F (802-816C)

Soak for 30 minutes for the first inch (25.4 mm) of thickness, plus 15 minutes for each additional inch (25.4 mm).

Quenching: Oil quench to a temperature no lower than 150-125°F (66-51°C).

***Note: O-1 is somewhat prone to quench cracking, especially if there are significant changes in section thickness and sharp internal corners. The oil quenching should be performed so that the heat removal is as uniform as possible in all areas of the part being quenched. Be sure to remove the part from the oil before the temperature drops to ambient temperature.

Suggested quench oil: Parks AAA, McMaster 11-second, Houghton G–expected as quenched hardness may be lower if a slower quench oil or non-industrial quench medium is used. Parks 50 is not recommended. Heat oil at a temperature of 300 to 400°F (149-204°C) is recommended.

Tempering: Temper immediately after quenching. Do not allow the part to cool below 125°F (51°C). The typical tempering range is 350 – 400°F (177 -204°C).

Hold at temperature for 1 hour per inch (25.4 mm) of thickness, 2 hours minimum, then air cool to ambient temperature.

To minimize internal stresses in cross sections greater than 3 inches (76.2 mm) and to improve stability in parts that will be EDM’d after heat treatment, a soaking time of 4 to 6 hours at the tempering temperature is strongly recommended.

Coating: ATP-641, Turco, or similar high temperature anti-scale/decarburization coatings can be used in replace of foil to reduce scale or surface decarburization.

Austenizing: Heat oven to Austenizing temperature (1475°F / 800°C)

When oven reaches Austenizing temperature, place material in oven and soak for 10 minutes. Soak time can vary from 5 to 15 minutes based on heat treating equipment and cross section but in most cases, a 10 minute soak time is ideal.

**Do not put blades in oven when cold, insert at or just below austenizing temperature–temperature variances is for difference in stock thicknesses and a window of margin for error.

Quenching: Suggested quench oil: Parks 50–expected as quenched hardness may be lower if a slower quench oil or non-industrial quench medium is used.