Spirograph 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.

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.

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.

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

Austenitize: 1950-2200°F (1065-1205°C), hold time at
temperature as shown in chart. Thick cross-sections and larger pieces
may need longer austenitizing time.

Quench: Plate quench, air or positive pressure
quench (2 bar minimum) to below 125°F (50°C), or salt or interrupted oil
quench to about 1000°F (540°C), then air cool to below 125°F (50°C).

Cold Treatment: A cold treatment may be used after
the quench to decrease retained austenite and increase hardness.
Tempering before the cold treatment decreases the effectiveness of the
cold treatment but also decreases the chance of warping or cracking. A
freezer treatment at -10°F (-23°C) has no effect unless performed
directly after the quench with no delay.

Temper: Double temper at 300-450°F (150-230°C). Hold for 2 hours minimum each time.

NOTE: Tempering above 750°F (400°C) results in a decrease in corrosion resistance.

Size Change: +0.05 to +0.10% when fully martensitic.
The presence of retained austenite may reduce the net growth. When
tempering at 300-750°F (150-400°C), freezing treatments may be necessary
to minimize retained austenite.

1. Begin with your XHP core 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 – 1,900°F/1049°C.
3. Place your wrapped damascus in the furnace/oven.
4. Soak your damascus for 20 minutes at austenitizing temperature – 1,900°F/1049°C .
5. Plate Quench to room temperature. You may also air quench or oil quench.
6. Optional - Cryo damascus at -100°F/-73°C for one hour. After air warm to room temperature
7. Temper for 1 hour at 400°F/204°C. Aim Hardness 61 HRC