Intro: How to Electro-Etch a Solid Metal Plaque
This is a technique that has been used by humans for a very long time.
Learn how to create a deep electro-etched metal plaque with household items or items from the hardware store in this Instructable. There are no hazardous chemicals (except dihydrogen monoxide and salts of sodium and chlorine), no dangerous voltages, and no toxic chemicals to dispose of. Be aware that the metal that disappears from your etched metal does end up in the water, so you will need to pay attention to any local laws about disposal of metal particulates.
This is a great technique that makes it really easy to go from virtual artwork of any type to a dimensional 3D surface. From there you can use it ti burnish and emboss paper, create molded items, make stamps, steam punk data plates, or anything else where you need to have 3D art from your 2D computer graphics artwork.
In this sample project, I will be creating the plaque from a 1/8" rectangle of brass as shown in the second photo.
So read on if this is something you would like to be able to do yourself.
Step 1: Here's What You'll Need
- Piece of brass, bronze, aluminum, steel or stainless steel, or any other metal
- Vector graphics program or other program to create the art for the CNC vinyl cutter
- CNC vinyl cutter
- Self-adhesive vinyl sheet for the vinyl cutter, any color is fine
- Tub large enough to hold your piece of metal
- Battery charger or charged car battery (or other similar DC power supply of 5 to 10 amps or more)
- Wires to connect the power supply to the piece of metal
- Sacrificial piece of metal (preferably stainless steel, but any metal will work)
- Electrical tape
Step 2: Create the Artwork
Use your favorite vector graphics program to create the artwork. I used Adobe Illustrator, but you could use any vector-based design software including Autodesk Inventor, Autodesk 123D, Inkscape, or others. Any shapes you create will result in the raised areas on your finished plaque, and the areas where there is no artwork are the areas that will be etched away. Try not to make the details too small because the vinyl cutter doesn't really do a great job with tiny cuts.
You might need to perform an operation to convert any live text into vector outlines. The resulting artwork from this process is shown in the second photo.
The artwork shown is from my first pass through this project. Because the very tiny type of the tagline under the TechShop loco ("BUILD YOUR DREAMS HERE") and the "TM" by the letter "p" in the TechShop loco were peeling off on their own, I took those out of the artwork.
Step 3: Cut the Mask With the Vinyl Cutter
Use the CNC vinyl cutter to create the vinyl mask. The exact procedure will depend on your particular vinyl cutter. After you have cut the vinyl, "weed" out the unwanted areas from the cut leaving only the parts of the artwork which will represent the un-etched areas or high areas on your plaque. After the unwanted areas are weeded away, place the backing sheet over the face of the vinyl mask and peel off the original vinyl backing sheet.
This vinyl cutter is at TechShop San Francisco, but all TechShop locations have a CNC vinyl cutter.
Step 4: Apply the Vinyl Mask to the Metal
Clean the metal completely and make sure it is dry. Apply the vinyl mask to the metal, burnish down all the pieces and peel off the backing sheet.
Instead of "weeding" the unwanted vinyl before you place it onto the target surface, you can also just apply the entire cut vinyl with the backing sheet, and then weed it after it is on the target surface. In this case, I found that to be much easier.
Step 5: Prepare the Metal for Etching
Connect a piece of wire to the back of the metal. You can do this with solder, an alligator clip, or by taping the stripped and splayed wire to the back of the workpiece with electrical tape (as I am doing here), or any other method you can think of. After the wire is securely attached, wrap the back of the metal with electrical tape or an extra piece of vinyl sheet. Cover all areas on the back and sides that you do not want to be etched. Any metal that is exposed will be etched.
Step 6: Prepare the Sacrificial Metal Piece
Connect another wire to the piece of sacrificial metal you have selected. In this photo, I am using some scrap galvanized steel for the sacrificial metal, but stainless steel is the best because it doesn't degrade and keeps the salt water cleaner. You do not need to mask off anything on this piece of metal as it will not be etched.
Instead of a sacrificial piece of metal, you could use a stainless steel pot and put the negative (-) alligator clip right on the rim of the pot. You would then put the workpiece into the pot, along with the salt water, and etch right in the pot. You just need to make sure that the workpiece does not contact the pot electrically.
Step 7: Prepare the Etching Tank and Salt Water
Measure out enough water to cover your pieces of metal by about an inch or two, and mix a lot of salt into the water. The more salt, the better it will conduct electricity and the better it will etch your metal.
Step 8: Prepare to Electro-Etch
Place your pieces of metal in the tub of salt water. Connect wire from the piece of metal you want to etch to the positive (+) terminal of the power supply, and connect the wire from the sacrificial piece of metal to the negative terminal (-) on your power supply. Then place the pieces of metal in the tub of salt water and place them as far apart as possible. Make sure the side of the plaque that you want to etch is facing up.
Step 9: Electro-Etch Your Plaque
Turn on the power supply, and you should see bubbles start to come off the surface of your plaque. Leave it to bubble for as long as you want. The longer you leave it bubbling, the deeper it will etch. If the salt water becomes really dark after a while, you can turn off the power supply and replace the water with new salt water and continue. Be careful if you let it etch too long because you will start to get "undercutting" where the metal starts to get eaten out from under the vinyl mask.
In the photo, you will see a divider separating the tank's right and left halves. The divider is only a chopstick and is only at the surface of the salt water, and serves to keep the red scum on the left side of the tub so I can see the plaque as it etches.
Step 10: Behold Your Creation
When you are happy with the depth of the etching, turn off the power supply and remove the plaque from the tub. Rinse it off, and remove the vinyl and tape. Remove the wire. Your plaque is complete!
After I etched this plaque, I took it over to the sandblasting cabinet and sandblasted the whole surface, then I used an orbital sander to smooth the surface of the raised features to get the look that you see.
After I was done, I noticed that the copper/zinc chemicals in the salt water had stained my finger nails a beautiful shade of turquoise. This was an undesired effect. i suggest that you wear rubber gloves when you reach into the tank to grab your workpiece!