As the prices of zinc and copper continued to rise, many craftsmen who made etching designs out of metal turned to steel. Although not as beautiful as copper, steel is better than zinc and more durable, especially when used for printing plates. Some types of steel can be acid etched, such as mild steel and stainless steel. Read on to learn how to etch steel.
Step
Method 1 of 2: Preparing Steel for Etching
Step 1. Determine the type of steel you want to etch
You can etch stainless steel, mild steel, or high carbon steel. The type of steel to be etched will determine the best type of acid or chemical to use for etching.
Step 2. Remove the burrs (rough parts of the metal sides) on the steel edges
Sand the burr on the side of the steel you want to etch. You can leave the burr on the other side if you are etching the steel plate.
Step 3. Rub the steel
Use a chlorine cleaner to scrub the steel in circular motions using an abrasive sponge, wire brush, fine steel wool, 600 grit (roughness) wet sandpaper, or corundum sandpaper. The surface of the steel should be slightly rough to grip the retaining material, but not too rough as this could create unwanted extra lines in the design.
Step 4. Wash the steel with water
Make sure the water covers the entire surface of the steel.
Step 5. Clean the steel a second time with isopropyl alcohol
Method 2 of 2: Etching Steel
Step 1. Select the image you want to etch onto the steel
You can draw your own by hand or duplicate an existing image on the steel surface. Depending on the image transfer method used, you can create a simple or complex design.
- If you want to duplicate an existing design, use an image that has high black and white contrast.
- If you want to make and sell etching prints, use images from the public domain or seek permission from the copyright owner (if applicable).
Step 2. Transfer the design to the steel surface
You can move images in several ways, which are described below. Understand that whatever method is used to move the design, the image will be printed upside down on the steel surface. If you want to use the etched steel plate only for decoration (not for printing), this is not a problem.
- The oldest method of transferring designs is coating the steel with a liquid varnish or wax-like material (such as beeswax), or even enamel paint or nail polish. This layer is called ground. Next, scratch the design into the ground using a needle or wide-bladed cutter. (This is similar to chopping wood.) The ground will serve as a shield so the etching acid doesn't remove the part of the steel that's covered by it.
- Another method is to cover the surface of the steel with a permanent marker where the acid doesn't want it to be removed and leave other areas exposed that the acid etching will remove. You may have to do some testing with a number of brands or colors of permanent marker to find the marker that is best at resisting acid.
- The third method is to make a stencil ironing which can be done by photocopying the design onto transfer paper or printing it on glossy photo paper using a laser printer. Stick the paper on the steel surface (with the printed part of the image under/adhere to the steel), and use a high heat setting. Next, iron the paper in a circular, smooth motion for 2-5 minutes. (Apply gentle pressure if you are using transfer paper; or press hard if you are using photo paper). After that, you can remove the paper. (Transfer paper will come off on its own, but photo paper must be soaked in hot water to make it soft and removable.) Ink transferred to steel surfaces will be resistant to etching acids.
Step 3. Cover the steel edges
You can tape the edges of the steel or paint them. Whichever method you choose will make the edges resistant to acid etching.
Step 4. Select the acid you want to use to etch the steel
Some acids that can be used include muriatic acid (hydrochloric) or HCL, nitric acid (HNO3), and sulfuric acid (H2SO4). Some non-acidic materials that can form acids when mixed with water, such as ferric chloride (FeCl3) or copper sulfate (CuSO4), can also be used as etching chemicals. The strength of the acid will usually determine how quickly the steel is etched, or "bitten". Acids and etching chemicals can be found at chemist or electronics supply stores.
- Usually, ferric chloride must be mixed with water in equal proportions to form a hydrochloric acid solution. This solution is usually used to etch copper, but it can also work well for etching stainless steel. It can also be used on metals that are resistant to pure acids. However, ferric chloride can puncture the surface of the object if not handled properly.
- Copper sulfate is better for etching mild steel than stainless steel. It's a good idea to mix it with sodium chloride (NaCl or table salt) in equal proportions to avoid forming a copper layer on the steel which could stop the etching process. This blue solution will gradually fade as etching progresses and become clear when the process is complete.
- Nitric acid is usually mixed with water (one part acid and three parts water). You can also mix it with acetic acid (vinegar) or hydrochloric acid, in equal proportions.
- Sulfuric acid should only be used in concentrations (percentage of ingredients) of 10-25 percent. Usually, aqueous solutions are more effective than concentrated ones. However, acids usually take longer to etch steel than chemicals that turn acidic when mixed with water.
Step 5. Soak the steel into the etching acid bath
In general, you should face the steel plate toward the bottom of the solution so that the metal chips that fall off from the etching acid fall to the bottom (into the solution) and don't stick to the plate. This will result in clearer lines on the etched steel. If you are facing the plate upwards, brush off any dissolved metal debris using a soft bristled bristles or brush. This will also remove any bubbles that appear. (Bubbles can hinder the etching process, but can also result in an attractive design if left as is.) Allow the steel plate to soak in the etching acid until the lines are cut to the desired depth.
- Whichever method you use (whether facing the steel plate up or down), make sure that the plate does not stick to the bottom of the immersion container in some way. (This is especially important if you place the plate face down).
- Periodically tap the chemical container used to soak the steel to keep the solution moving.
Step 6. Take and clean the steel plate
Remove the acid adhering to the plate by washing it with water. If using a strong acid, you may need to neutralize it with baking soda. After that, you must remove the retaining material that is attached to the plate. Depending on the materials used to create the design, choose one of the methods below:
- Use turpentine to remove ground from paint and varnish. (Use acetone to remove nail polish.)
- Use alcohol, steel wool, or methyl hydrate to clean the ground of materials such as wax.
- Remove the water-soluble ink using running water. Use alcohol to remove water-insoluble ink.
Tips
- You can use etching acid more than once to etch steel. Each time the acid is used, the etching time of the steel will be longer than before (with the same depth).
- Another method for etching steel is anodic or galvanic etching. In this method, the steel plate is connected to the positive pole of the 12 volt battery, while the chemical solution for etching is connected to the negative pole. The etching material (or electrolyte) in this method is not an acid, but a chemical that can act like an acid when ionized by an electric current.
Warning
- If the etching acid is too weak to etch the steel, dispose of it in a hazardous waste container. Don't throw it in the gutter.
- Always do the etching in a well-ventilated area, and wear protective goggles and rubber gloves to protect eyes and skin from etching acids. It is recommended that you have clean water in your work area to flush your skin or eyes in case of accidental contact with an acidic solution.
- When diluting the acid, pour the acid into the water, not the water into the acid. Pouring water into a strong acid can make it hot and overflow from the container. If you pour acid into water, the heat from the acid will be safely dissipated by the water.
