Metallurgical

Steel Etching Procedure

Procedure by Ruth Kramer.

NOTE: There are many etchants available to use for steel. The correct etchants depend on the type of steel in your sample. Our labs commonly use 2% Nital, but we can formulate most any type of etchant needed.

One resource for learning more is MSDS Xchange, which includes an extensive collection of material safety data sheets. (See MSDS in General Lab Safety under Support.)

General Precautions

• READ THE MSDS SHEET FOR ALL CHEMICALS IN THE ETCHANT YOU WILL BE USING.

• PRESS THE GREEN FAN BUTTON BEFORE YOU START TO MAKE SURE THE FAN IS RUNNING.

• ALWAYS add concentrated acid to solvent, stirring.

• LABEL ALL CONTAINERS, even if it is just water or alcohol!!!! Leave the fan running if you have an open (and labeled!) container in the hood.

• DO NOT leave open containers in the lab when you are done; always empty the beaker and rinse well. Check the MSDS sheet for proper disposal of the etchant, and if allowed, empty corrosive liquids down the drain with plenty of water. When disposing of paper towels, swabs, etc. which have been used to absorb corrosive liquids, RINSE THOROUGHLY before throwing in the trash.

• When using concentrated acids, or any solution containing HF, wear an apron as well as gloves and safety glasses.

• Always do all etching in the hood. NEVER HANDLE PERCHLORIC ACID IN THIS LAB. If you need this type of etch, SEE RUTH.

2% Nital Etching Procedure - Steel

1. Have a wash bottle of methanol handy. Pour a couple of milliliters of etchant from the stock chemical into a small beaker, rather than dipping into the stock and risking contamination. If the etchant contains HF, use plastic!
2. Open the tap and allow water to run, turn on the fan, air, and light.					VIEW	Click VIEW again to hide. Click image to open a large version in a new window.
3. Take a small amount of cotton and make a swab.					VIEW	Click VIEW again to hide. Click image to open a large version in a new window.
4. Put on gloves and safety glasses, and apron if needed.					VIEW	Click VIEW again to hide. Click image to open a large version in a new window.
5. Pour a several ml of etchant into a beaker (Use plastic if your etch contains HF!)					VIEW	Click VIEW again to hide. Click image to open a large version in a new window.
6. Dip the swab into etchant. Apply to mount in a circular motion, until you just begin to see a haze appear on the polished surface. RINSE IMMEDIATELY under warm running water. Rinse with alcohol, dry.					VIEW	Click VIEW again to hide. Click image to open a large version in a new window.
7. THE FACE, SIDES, AND BACK of the sample must be COMPLETELY DRY before putting it on the microscope.					VIEW	Click VIEW again to hide. Click image to open a large version in a new window.
8. Discard the unused etchant, flush the drain with water, turn off the hood, water, fan, and lights.