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

You will need the following items and supplies:

• 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
• Salt
• Water
• 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!

Comments

[EframG]

You should not use stainless steel as a sacrificial electrode, the stainless property is due to the presence of chromium atoms into the alloy. The chromium atoms will become oxidized and enter solution... you do not need to take my word for the toxicity of chromium salts, not only are they extremely toxic, such as chromium(VI) or hexavalent chromium, the disposal of chromium salts is also very highly regulated by the EPA and tested for during normal drinking water testing and as such, illegal disposal of chromium waste is also extremely illegal.

[Domingo69]

No oxidation whatsoever is taking place on the "sacrificial" (not a very relevant name IMO) electrode. On the contrary a reduction is taking place : the H ions become gaseous Hydrogen. Chromium or whatever metal present will not be affected. Furthermore, given enough time, the Copper ions coming from the etched plate would also be reduced and become metal again and could start to cover the sacrificial sheet. This is indeed an industrial process for refining Copper.

[jonf3n]

@EframG was talking about *stainless steel* not copper.

[Domingo69]

I know. The Copper I mentioned comes from the OTHER plate, the one being etched (etching = chemical transformation of Copper metal into SOLUBLE Copper ions). What I was saying is that the stainless steel electrode will NEVER be attacked. So the Chromium (and whatever metal making up the electrode) will remain unaffected, and the comments about toxicity of dissolved Chromium, entirely irrelevant.

[train2better]

This method works great however I can achieve a deeper and cleaner etch when the work piece is facedown resting on a pvc nipple. My only struggle is the fine line sections of my 3m vinyl, lifts of the work piece during the etching process. This causes distortion in the fine details. If its just a simple silhouette image I don't have a single problem. Do you have any suggestions for this problem?

[JeromeD44]

Hi,
I am a sculptor and I use Copper Sulfate + salt (without electricity) for etching my iron sculptures. (About 40 to 80 liters per sculptures).
Do you think I could use this system to etch without copper sulftate ?
Although, what is important ? Voltage or Amps ?
I was thinking on turning a microwave amp to do that.
What do you think ?

[curtlezumi]

You probably could use an electrochemical etch instead of salt and copper sulphate. With electrochemical etching, the salt ions Get a helping hand with the electricity but electrolyte is a poor conductor. So the bigger your tank, the more baseline voltage you’ll want to compensate for elecrolyte resistance. Overall the current is what is doing the work because it directly relates to the amount of salt ions actively etching your work. On a small scale, etching starts with even 3 or 4 volts, but is very slow.

An AC etch tends to cause a darker stain but little metal removal. Direct current creates a deep etch.

I would suggest car battery charger for a cheap power supply. Not sure how to work around any safety features but limiting current may help. A microwave amp is likely too high of a voltage and is an AC output to the best of my knowledge. Most times dc is the better choice for etching.

If you have a variable power supply, You can increase the voltage up to the point the work piece starts producing bubbles then back down a bit. The work piece is the one attached to the positive lead. The sacrifice piece should always produce bubbles. However, Bubbles on the work piece indicate the voltage is high enough to break down the water which is electricity not going into to etching.

Finally, it is important to consider a few safety concerns. First, it is good to have some form of current limiting in the circuit. This can easily be done by including a lightbulb in series in the circuit. That way if you accidentally bump the work and sacrifice piece together the lightbulb limits the current and avoids damaging the power supply (or blowing a fuse). The next concern are the gasses produced. Even in the example here, I would want to consider ventilation because the gas produced on the sacrifice side is hydrogen. Even a small percentage of hydrogen, like 12%, in air can explode and it it good at floating up and collecting where lights and the possibility of sparks are.

Venting the gasses produced outside is recommended and even a small amount of airflow should be enough for most projects. For large etches, a deliberate strategy may be needed. The last safety concern is the remaining enchant solution. It is full of dissolved metals and should not be dumped down the drain. It can be reused and generally cleans well by letting the rusty scum settle out and pouring off the clean liquid. Personally if I must dispose of it, I let it evaporate (which can take months), and then throw out the small amount of salts that are left. If your left with more than a cup of waste salts, check with your waste disposal company.

[reichenbach1976]

I made a small 1.5 amp electro etcher from a 12v DC wall adaptor but I want to use a car battery charger. Im reading some have safety features that wont let this method work. What charger features should I avoid for electro etching (ie. thermal overload protection, self resetting circuit breaker)?

[KentR2]

Hi,
I just tried this with sheet steel. It worked great! However I am wondering what I should do with the solution now. I used salt water and in the course of etching it turned green brown. I'm assuming this isn't safe to put down the drain or in the yard but have no clue what to do with it. Any input would be greatly appreciated!
Thanks!

[EframG]

If all you used is steel, than the green color is most likely Fe(II) salts, which are relatively non-toxic. If you left the solution sitting for some time it will probably become all brown as Fe(II) will oxidize easily. The nice thing about iron is, as far as transition metals go, it is very safe.

[TechShopJim]

Hi KentR2...

Wow, that is a deep and loaded question!

I'll just say that there are a LOT of people on here with strong opinions about what is dangerous and what is not, and what will utterly and completely destroy the earth if it is disposed of in certain ways. You can look at the earlier comments to see what I mean. I will let those folks reply since they are the experts (actually, they're not, but they do have opinions...which as they say, we all have opinions and something else.)

I'm going to stay out of that argument because I don't know all the legal and physics issues involved, and I don't pretend to know, and I am not required to know before I'm allowed to write an Instructable, and that wasn't what I was trying to share with my Instructable.

From my research, you can pour just about anything on paper towels or newspaper and let it dry completely, then discard it with other dry waste. I've never understood why it matters if there is water in the substance when you throw it in the garbage, but that's what people keep stating, so OK.

Getting back to basics, I'm really glad that your etch worked! Awesome! Can you post some pictures?

[VulpesNoctem]

Cat litter too!
I do this for brake fluid. Put the pile of the stuff in a bin, throw it next to the shop's exhaust vent, let it stay there until it's dry. Toss it in the trash.
Never done it with so *much* fluid before, tho, so this'll be fun.

Jim, I'd guess it'd be because our sanitation workers and environmentalists don't want all that stuff being dumped onto the roads when the garbage truck crushes the container ya put the fluid in. That's just gonna let it run down and out of the truck, and into the sewers. So basically just pouring it down the drain in another way.
That, and I'm sure the garbage guys don't want liquids sloshing all over the place more than they already do. :)

[Jedi_zombie85]

Very nice write up, A friend of mine is "apparently" using a similar technique to jazz up an exhaust on a bike, not sure how well it will turn out but will deffo post the results

[LeeK64]

So im attempting to etch some steel. I bought a new battery charger and its not working at all. Do new battery chargers have a safety switch that keeps ot from working?

[VulpesNoctem]

Short version: Maybe
It looks like TechShop was using a Schumacher SpeedCharger. Shumacher makes versions that are smart, like the kind it sounds like you have, and ones that are dumb, that just put out current. The latter is the one you need for this. They're less desirable when dealing with batteries, because they can overcharge and destroy the battery, but in this scenario, you don't want one with the 'smart' circuits that may only work safely--e.g. after it's verified it sees a real battery that it's designed to be charging.
However, you could use your new safe battery charger to charge up a large battery, and then use it to complete this project. It just needs to be able to put out high amperage...or lower amperage, and it'll go slower. Or so is my understanding.

[MakerIan]

Rapid bubbling means you are disassociating water. I use 5v from a pc power supply for my etching. I like to use an electrode that is as large or larger than my etch target. Things like proximity, solution concentration, total amperage all make a difference on etch speed. My setup is basically a copper grid electrode that sits 2 inches(5 cm) from the target face. I also use copper sulfate as my electrolyte, but I only process copper materials.

Also, for those in the US anytime you do electrochemical etching or plating your waste water is epa regulated.

Stainless steel is particularly bad as the electro-etching converts the chome to hexavalent chromium which is nasty nasty stuff and should never be put down a drain.

[dbunting]

Inhaled hexavalent chromium is recognized as a human carcinogen. Workers in many occupations are exposed to hexavalent chromium. Problematic exposure is known to occur among workers who handle chromate-containing products and those who grind and/ or weld stainless steel. Workers who are exposed to hexavalent chromium are at increased risk of developing lung cancer, asthma, or damage to the nasal epithelia and skin. Within the European Union, the use of hexavalent chromium in electronic equipment is largely prohibited by the Restriction of Hazardous Substances Directive.

[tkip]

Is hexavalent chromium created only if steel is the target of the etching, or does it also apply if it is used as the sacrifice piece? Is it a vapor, a sludge?

[MakerIan]

The chrome in question is only a product of electrically dissolving Stainless steels. Stainless is a combination of steel (iron and carbon) and chrome. So when etching away stainless the chrome dissolves into solution making it soluble and toxic. So not a gas, some in solution and some as sludge once the solution is saturated.

And only if etching stainless is it going to liberate chrome. The sacrifice piece gains metal from the etching piece so you would be plating the stainless which is fine.

[tkip]

Thanks! So, I do electro etching of bronze in Cupric Nitrate (hoping to switch to saltwater, but not sure it works on Bronze) and I am using a piece of Stainless Steel grate as the Cathode/Sacrifice... and that piece of Stainless is dissolving gradually!... it's not accumulating metal, as one would expect, it's getting covered in what looks like rust, and falling away around the edges. Any ideas why, and do you know if this might contain hexavalent chromium? Sorry to be such a pest, but there are so few people out there who have knowledge about this. Thanks again!