The method I am writing about here is the copper acetate method. Rather than buying copper acetate pre-made, we will make it ourselves.
I wanted this instructable to be as easy as possible, safe as possible, and as cheap as possible.
Copper plating has a variety of uses. Aesthetically, it can be used to create a steampunk look on otherwise ill-fitting metals. Anodizing the object after plating can create brilliant, multicolored objects. Electrically, it creates a highly conductive surface for soldering or use in AC circuits (for the skin effect). It is also frequently used to prepare stubborn materials for other platings such as nickel and silver down the road.
If you like this instructable, but want a silvery finish instead of a copper finish, check out my nickel plating instructable!
On another note, I LOVE your questions! I have noticed that a few folks are asking the same questions, so I've added a "Common Questions" step/slide/section/whatchamacallit at the end of this instructable. Take a look there to get quick answers to most of the questions you might have. If you have a new one, comment below and I'll be happy to answer it and add it to my step/slide/section/whatchamacallit :D
A quick disclaimer - copper acetate, the chemical we will be making, is poisonous. The title "High Quality (and Safe) Copper Plating" is referring more to the fact that you don't need to play with insanely powerful acids that will burn your skin or ask you to open batteries. In the concentrations we will be working with, the process is fairly safe. However, do NOT drink the solution and be sure to wash your hands after plating and properly wipe down any surfaces that come near or into contact with your plating solution. Always supervise kids. That said, enjoy!
Step 1: Materials
Distilled White Vinegar (5% acidity or higher, grocery)
Hydrogen Peroxide (3% or higher, pharmacy)
Cameo Aluminum and Stainless Steel Cleaner (cleaning supplies)
100% Copper scoring pad (cleaning supplies)
Alligator Leads (electrical)
*6V Lantern Battery (camping)
1 pint, wide mouth mason jar (canning supplies)
Paper towels (paper supplies)
Nitrile gloves (cleaning, pharmacy, or DIY)
Note that if you plan on electroplating very large things, you will need to buy a lot of vinegar, hydrogen peroxide, copper, and larger containers.
You can substitute the copper scoring pads for scrap copper pipe or wire. The one (huge) benefit to using the scoring pads is that they have a very high surface area which will be useful in later steps.
*See my note in the last "step" about the 6V lantern battery. You can replace it with a 1.5V battery or a couple AA's if you'd like or it would save you some money.
Step 2: Creating Your Electrolyte 1/2
The first thing you need to do is add equal parts of distilled vinegar and hydrogen peroxide into your mason jar (ie "half and half"). Your ratio does not need to be exact. The hydrogen peroxide will cause the copper to oxidize quickly. This, in turn, allows the copper to react with the acetic acid in the vinegar quickly.
Heat the mixture in the microwave until it steams gently (about 1 minute, 45 seconds for me). This can also be done on the stove over low heat in a glass (not metal) container. The reason we are heating up the mixture is so that our copper reacts more quickly in the next step.
Step 3: Creating Your Electrolyte 2/2
Stretch out the copper scouring pad and break it into two pieces. Note that the copper wire may be sharp, so you may want to use gloves to do this.
Place the copper into the warm vinegar/peroxide mixture. Screw on the lid and gently swirl.
As time passes, the liquid in the jar will become more and more blue. The blue color comes from the copper ion in the copper acetate that is being created. The longer you leave the copper in the mixture, the more saturate and the more blue the solution will become.
Note that the goal is NOT to create a very saturated copper acetate solution. In fact, it is far better to have a weaker solution than a stronger one. When we start electroplating, we want the copper atoms to create very even layers on our object. If the copper builds up too fast, it will not adhere well and you will get "burn" spots.
Step 4: Making the Copper Electrode
Take the first alligator lead and clip one end to your newly made copper electrode. Take the other end of the first alligator lead and connect it to the positive terminal on your battery. This is now your "anode". Place your anode into your copper acetate solution such that it is as far to one side of the jar as possible.
Step 5: Preparing Your Metal Object for Electroplating
To prep my surfaces, I like to use Cameo Aluminum and Stainless cleaner. It costs only a couple dollars and works wonders.
Don your nitrile gloves and grab your object. Take a small dab of liquid dish cleaner and scrub your coin and then rinse well (your gloves too). This will remove most of the grease, dirt, and grime from your object.
Combine a small amount of Cameo and a couple drops of water to make a paste and scrub your object again. Cameo has an acid, as well as abrasives, that will remove any oxidation. It is VERY important that this is done well and completely. You can tell that you are done when the entire surface is an even, dull gray (for grey metals at least).
Rinse your object thoroughly and pat dry with a paper towel.
Now, attach the second alligator lead to your object. Try to clip the lead to an inconspicuous place if possible. If there is not an inconspicuous place (for example, a coin doesn't have any hidden parts), you will need to move the clip frequently during plating.
Step 6: Electroplating
Lower your object into the acetate solution such that it is fully submerged. Holding the wire, gently move your object back and forth in the solution slowly rotating it.. After a few seconds, you should notice the base metal starting to turn yellow. This means that you have done everything right so far. The longer you swirl your object, the thicker your plating will be and the redder it will become.
IMPORTANT: You must keep your object moving while it is being electroplating. Failure to do so will give you "burn spots" where the copper accumulated too quickly. While the burn spots can be buffed out, the copper will not have adhered well to the base metal and will flake/rub off easily.
IMPORTANT: Keep your object at least an inch or more away from your copper electrode. Again, you will get burn spots for the reasons stated in the above warning.
Step 7: Post Prep
The cool thing about copper plated items is that the copper plating allows you to plate it with other, trickier metals. For example, nickel doesn't like to adhere to some steels without some coaxing. So, you can apply a light copper plating before applying a nickel coat.
On another note, you can save your left over copper acetate solution for later plating uses as well. Just place the lid on the jar and seal tight. Make sure to label it "POISON - COPPER ACETATE" and store it away from the tiny hands of kids. Rinse everything that comes into contact with the solution well and store in a safe place.
Step 8: Common Questions
It depends. Certain metals play nice together, others do not. The ones that do not are called "dissimilar metals". In the picture, you'll find a table I borrowed from RFI. The table is designed to let you know when a galvanic reaction might occur causing corrosion. For our purposes, it also tells us which metals are compatible and which are not. The lower the magnitude of the number (aka the absolute value), the more compatible (ie similar) the metals will be. If you are trying to plate a metal that is not compatible, you may need to plate with nickel or another metal first. Aluminum, for example, should be plated with nickel before it can be plated with copper. You can find my nickel plating instructable here: https://www.instructables.com/id/High-Quality-and-safe-Nickel-Plating/
How do I plate non-conductive objects?
First, you need to make them conductive. You can do this with conductive paints, conductive glues, and even metal leaf (think gold leaf) as long as whatever you are coating your surface with is not water soluble. I haven't experimented much with this myself which means you will have to. Send me a message with your results and I'll post them here for others to reference.
How much voltage/current do I need?
As little as possible. The lower the voltage and current, the better results you will get. You need a minimum of 0.5V DC to plate with copper. A C or D cell battery will give you pretty decent results. If you don't have access to lower voltages, you can put the electrolyte into a big container and move your electrodes as far away from another as you can - the increase in distance will also increase the resistance of the circuit and decrease the current.
Can I use copper chloride or another electrolyte instead of making it with vinegar and such?
Yes, you can. I just like the idea of making my own chemicals. You can get root kill (which are green crystals if I recall) at your local hardware store for relatively cheap.
Can I use other acids other than acetic acid (vinegar)?
Yes.....but be careful... This instructable was written for average Joes and Jolenes, not chemists. Other acids can be significantly dangerous as well as release some very nasty, very toxic chemicals into the air. Unless you are an experience chemist (ie you have an actual degree, not just AP Chem in high school or Chem 111 in college), I would not recommend playing with other chemicals.
Is plating coins illegal?
The first thing I want to point out is that I'm only using coins because they are everywhere and cheap by definition. The copper and nickel content make them ideal for small experiments. This isn't a "how to plate coins" instructable, they are just handy and recognizable. For those of you who took high school chem lab, you probably used quarters, dimes, and pennies for a couple different classroom experiments.
As far as the legality of plating coins, to my understanding, it is legal as long as you 1) Aren't removing metal from the coins with intent to sell that metal, 2) Are not trying to pass them as something they are not (ie a copper plated dime is worth 10 cents, nothing more), and 3) Aren't defacing the coins for malicious intent. As a personal disclaimer, this is MY understanding - take it with a grain of salt. If this is incorrect, I would welcome a friendly email or message from the US Treasury or other qualified persons.
Why are you using a 6V lantern battery when you say that lower voltages are better?
-The difference in plating quality between low voltages (0.5VDC is the lowest you can go) and 6VDC is not much. BUT, the time it takes to plate using 6VDC is a lot less.
-If you want lower voltages, you can do so by moving your anode and cathode farther apart. This is because your electrolyte acts as a variable resistor and the square resistance of your anode and cathode create two more resistors of a fixed resistance. The further your anode and cathode are from each other, the greater the resistance of the electrolyte, the greater the voltage drop across the electrolyte, the lower the voltage between the cathode and the electrolyte directly touching it. Without taking an electronics class, this can be a little difficult to understand, so if you don't, you will just need to trust me.
-Good lantern batteries will last a very long time. They have many, many AA batteries in parallel which gives you more available juice and higher current if you want it.
-Lantern batteries are easy to clip alligator clips to and don't need battery holders.
-As the battery drains, its internal resistance will not raise significantly and its voltage will not drop much due to the highly parallel internal battery connections. This gives you more consistent results.
Can I plate Aluminum?
I would avoid it. Aluminum is just one of those metals that don't plate well. If you are looking for a corrosion-resistant finish, you can anodize the aluminum to create a clear oxide layer that is extremely corrosion resistant. If you are looking for a colored finish, you can get dyes that absorb into the oxide layer and stain it whatever color you want (this is actually what Apple and other companies do to make different colored iPods).
Can I use copper plating to keep steel parts from rusting?
No. Absolutely not. This is for a couple different reasons.
- Copper patinas (ie rusts) and can eventually flake off over time exposing microscopic and macroscopic holes through to your base metal. As salt, water, and oxygen reach the base metal, it will rust underneath your plating causing more plating to flake off and ....you get the idea.
- Copper will create a galvanic reaction (which is how most batteries work) with the iron in the steel when your object is placed in water. This will cause your steel parts to rust EVEN FASTER. If you want to test this, place a piece of copper in salty water with a piece of steel touching it. It will start rusting like crazy in a couple hours or faster.