Introduction: Make Golden Coins (really Easy)
Turn your lame copper cents and pennies into gold with this simple trick, King Midas hates him!
Well, it's not really gold, but the results look just as cool, you could easily fool somebody into believing it's the real deal. Amaze your friends and family and maybe some cashier or bartender with these easy to make, shiny, golden coins.
This method works by applying a small coat of zinc to the copper coin and then using some heat to melt the zinc, fusing with the copper and creating a thin layer of brass, which has a similar color to gold.
This chemistry trick has been around for a long time but I haven't seen an instructable on the subject, so I decided to share my method which uses common household chemicals that can easily be obtained.
ATTENTION: This instructable deals with caustic materials and hot surfaces/objects, follow the steps under adult supervision.
Step 1: Materials
- Copper coins (The shinier the better)
- Zinc plate (Can be obtained from alkaline batteries)
- White Vinegar
- Sodium Hydroxide (aka Lye, a common drain cleaner also used to make soap)
- Power supply
- Plastic tray
- Glass of water
- Heat gun or electric stove
If you don't have a power supply you can use a couple of AA batteries in series.
Step 2: Choose Your Coins
Chose the coins you want to plate, the coins must be made out of copper or be copper plated, they also need to withstand temperatures of up to 450ºC in the case of plated coins.
If you can, choose the shiniest coins you can find, a shiny copper coin will keep being shiny after it's plated, while a dull coin will show a dull golden color. Shinier coins are also easier to clean and won't leave unplated spots due to rust or grease on the surface.
I chose some 2 and 1 Euro cent coins, 5 cent coins can also be plated but I didn't have shiny ones.
Step 3: Clean Your Coins
For the electroplating process to work the coins must be impeccably clean, they are first washed with regular dish soap to remove all the grease on their surfaces and then they're submerged in vinegar for a couple of minutes to remove any rust from the surface, then they're rinsed in water and transferred to a paper towel.
If your coins are very rusty you can clean them with a mix of vinegar and salt, although the final result will not be as good as with a new, shiny coin.
Step 4: Prepare Your Setup
Fill the plastic container with water, one tea spoon of sodium hydroxide is added per 1/4 of a liter (1 cup of water), the zinc plate is placed at one side of the container. Sodium hydroxide reacts exothermically with water, stir the solution for the first minute to dissipate the heat from the bottom.
Connect the positive wire of your power supply to the zinc plate, and the negative wire of the power supply to the tweezers, hold the coin with the tweezers by the rim.
Set the voltage of your power supply between 1.5 and 5 volts, more voltage will result in poor plating. The voltage will depend on the concentration of the solution and the distance from the coin to the plate, you can play around to find the voltage that works for you, any voltage in that range will work, but with lower voltages it will take more time.
Step 5: Plate Your Coins
With everything ready and connected submerge the coin in the sodium hydroxide solution, you'll see the coin starting to fizzle, releasing tiny bubbles. Rotate your coin around to plate it evenly.
The gases produced aren't toxic, they are oxygen and hydrogen, however, the bubbling might cause some of the solution to turn into a fine mist above the container, to avoid inhaling it, the experiment must be performed on a well ventilated area.
After a minute of two the coin should be fully plated, the copper color should not be visible anymore, instead, the coin should have a silvery coat.
After the coin is pulled out of the solution the potential is no longer present, so the zinc atoms in the coin will want to redissolve again into the solution, to prevent this, the coin is pulled out, rinsed in water and dried with a paper towel as quickly as possible. You can see how the zinc plating disappears if you leave the coin out of the solution while still wet for too long.
Once the coin is plated it should look like the image above. At this point you can end the process and keep your shiny silver coins, or turn them into gold with the next step.
Step 6: The Golden Touch
To turn the silver color to gold we need to heat the coins at a considerable temperature, enough to melt the zinc so that it fuses with the copper, mixing their colors to create a shiny golden coin. I did this using a hot air gun set to 450ºC (840F), but you can use an electric stove, letting the coins heat up on it's surface.
Fire can be used too, but I don't recommend it, since it easily produces uneven results.
When the coin heats up to temperature you'll see the color rapidly changing, then, the coin is carefully removed with pliers or tweezers, it's very hot, so leave it to cool down for some minutes.
Thanks for watching, I hope you liked it :)