Random San Mai

By taking your time and learning how to etch stainless Damascus and carbon Damascus steel properly, you’ll avoid problems like spots in your finished product. Damascus etching is done with a mixture of Ferric Chloride and Distilled Water, we use a 50/50 mixture. Before you begin, check the expiration date on your acid of choice to be sure that it’s not too old. Using expired acid causes problems with your etch, and you don’t want to find out after you’ve already started that your acid is too old to work properly. (Click here to buy the Ferric Chloride we use)

Step 1: Sanding

Bring your Damascus to a 400 to 600 grit finish. *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 acetone and pat it dry with a clean rag.

Step 3: Dilution

If you’re using ferric acid, dilute it with DISTILLED water until you have pretty close to a 50/50 ratio of acid to water. 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.

Step 4: Warming the acid

Warm if needed. The temperature of your acid should be between 70 and 120 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

With a wire, hang your damascus piece in the container of acid so that it hangs freely and doesn’t touch the bottom of the container.

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. Use a soft toothbrush and after 1 minute pull the Damascus from the etchant and lightly brush over the entire surface. Repeat this again at the 5 minute mark.

Let your piece remain in the acid for 10 minutes total or until you achieve the depth you want.

If there are sections that you don’t want the acid to etch then you can use nail polish to mask the material. Be careful to not brush the masked area when etching cause it can remove the polish.

Step 6: Neutralization

Remove your Damascus piece from the acid and dip it into a bath of baking soda for 10 minutes. Mix a generous amount of baking soda with distilled water to make your bath. Baking soda will settle to the bottom so make sure to mix it up well right before you drop your pieces in.

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, rinse the material thoroughly and then spray with Windex. It’s the ammonia in the windex that will ensure you have fully neutralized the Ferric Chloride. Pat dry with a clean rag.

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 Sand Paper (Optional)

This works best with flat parts that are deep etched. One of the steels within the damascus isn’t affected by the etch, which is what gives stainless Damascus that unique texture when it’s finished. Use a 2000 grit sandpaper 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. This can be tricky if the piece you are trying to sand isn’t flat, sometimes it’s just best to leave it as it is.

Some makers like to soak finished pieces in WD-40 over night to get a darker contrast. Results seem to vary with this but it won’t affect your material negatively if you want to try.

Click Here to Download "Etching Stainless & Carbon Damascus Guide".

1 - Begin with your Damascus product wrapped as tightly as possible in .002 SST foil. Use double folds on all sides to ensure a tight seal.

2 - Preheat your furnace to austenitizing temperature – 1,925 degrees Fahrenheit.

3 - Place your wrapped piece in the furnace and allow your furnace to cycle back up to austenitizing temperature.

4 - Soak your piece for 15 minutes.

5 - Remove Foil quickly and Quench in oil until it stops smoking. You can also Plate or Air quench.

6 - Temper twice at 350 degrees Fahrenheit for an hour each time.

**For advanced CRYO hardening, quench in liquid nitrogen for 4 hours, then re-temper once at 350 degrees Fahrenheit. For more information on cryo treatment, read through this forum thread.

**For rings and other small parts that don’t require a full heat treat we recommend using a torch and heating the material to a halloween orange. This is sufficient to harden the material and return the stainless qualities of the damascus back into the steel. Flaming will discolor the surface and prevent proper etching of the damascus so be sure to flame prior to final sanding steps.

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.

For knife damascus blades and similar parts made with annealed O-1 Damascus or San Mai with an O-1 core.

Use a temperature-controlled heat-treatment furnace for accurate, consistent heating.

Step 1: Apply an Anti-Scale Coating

Clean the material and apply ATP-641 or another suitable anti-scale coating according to the coating manufacturer’s instructions. Allow the coating to dry as directed before heating.

An appropriate coating helps reduce oxidation, scale, and surface decarburization during heat treatment.

Step 2: Prepare the Quench and Tempering Equipment

Prepare a suitable commercial quenching oil, such as Parks AAA. Bring the oil to the operating temperature recommended by its manufacturer, and use enough oil to fully submerge the piece and maintain effective cooling. Parks AAA is a suitable option for O-1.

Have the tempering oven ready at 400°F (204°C) before quenching so the first temper can begin promptly.

Step 3: Preheat the Material

Heat the material to 1250°F (677°C) and hold until it is evenly heated throughout.

Allow the steel itself to reach the preheat temperature before increasing to the hardening temperature.

Step 4: Austenitize — Heat and Soak

Increase the furnace temperature to 1475°F (802°C).

Once the entire piece has reached this temperature, hold for 30 minutes. Begin timing after the material has heated through; the time spent bringing it up to temperature is separate from the soak.

Step 5: Oil Quench

Immediately after the soak, transfer the piece into the prepared quench oil.

Keep it fully submerged and move it straight up and down to promote even cooling. Avoid sweeping a blade from side to side, which can contribute to warping.

When the steel reaches approximately 125–150°F (52–66°C), remove it from the oil, remove excess oil, and begin the first temper promptly. This temperature refers to the workpiece, not the oil-bath setting.

Step 6: First Temper

Temper at 400°F (204°C) for a minimum of 2 hours, beginning the hold once the piece has reached tempering temperature.

After the first temper, remove the piece and allow it to cool completely to room temperature.

Step 7: Second Temper

Repeat the temper at 400°F (204°C) for a minimum of 2 hours.

Afterward, remove the piece and allow it to air cool to room temperature. Complete both tempering cycles, with cooling between them. The 400°F setting falls within published O-1 tempering guidance, and two cycles with intermediate cooling follow Uddeholm’s O-1 procedure.

Final Hardness and Finishing

Confirm the final hardness using a suitable test area or representative sample. For San Mai, evaluate the O-1 core; a reading from the outer layers does not establish the core’s hardness.

The 400°F temper is a general starting setting. Select any adjustments according to the required hardness and verified results for the material. Published tempering curves provide guidance, while actual results depend on the material and heat-treatment conditions.

Once both tempering cycles are complete and the piece has cooled, proceed with final grinding, finishing, and etching.

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

Data is representative of controlled heat treating equipment (e.g. oven,salts, etc.) temperatures and industrial standard quenchant.

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

Austenizing: Austenizing temperature (1,450 to 1,480°F /801°C) Soak time varies 5 to 15 minutes based on heat treating equipment and cross section–soak times are reduced to minimum for people heat treating in a forge–forge heat treating without PID temperature control limits accurate means of maintaining temperature. If using calibrated, proper industrial equipment for heat treating, use the supplied extended soak times based on over all steel thickness.

**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.

Tempering: Once blade is quenched and near ambient temperature, blades should be tempered accordingly, the times suggested are to ensure even, consistent temperature.Figures supplied are as representative of industrial standards.*If using a small toaster oven or household kitchen oven for tempering, using a blade holding rack made from kiln furniture, a roasting tray lined with fine sand, or similar large object will help retain thermal mass to reduce wide swinging temperatures as the device fluctuates trying to maintain temperature.

Note: Final hardness values vary based on initial as-quenched hardness and percentage of conversion to Martensite. Only reliable testing methods, e.g. calibrated Rockwell hardness tester, can provide actual hardness values–hardness calibrated files and chisels are relative testing methods and inaccurate for true hardness value reading.

Temper twice for 2hrs.