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 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
  • Tweezers

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 :)

Comments

author
treymartin82 (author)2017-09-14

When you say "Aa batteries in line" would one of the big square batteries work? They usually go in lanterns. I cannot currently recall what they are called I apologize.

author
Victor805 (author)treymartin822017-09-14

Those are 6 volts if I recall correctly, a voltage between 1.5 and 5 volts is recommended, but you can make the solution less concentrated and see how that works for you. Maybe a 100 Ohm resistor in series with the battery would work too.

author
bpark1000 (author)2017-09-11

Be sure to state to get the zinc from "zinc-carbon cell", not "alkaline cell".

Yes zinc-coated roofing nails could be used. But be sure the zinc coating is hot dipped (looks rough and crystalline, as on a roofing nail, not smooth and shiny). If it is not, the zinc will be so thin that the zinc will be etched from the steel before you have enough zinc ions in solution to electroplate on the coin.

When heating the coin to alloy the zinc, be sure to do this in a well-ventilated area, as zinc heated to the melting point is volatile, will fume, and is somewhat toxic.

author
Victor805 (author)bpark10002017-09-12

The coin does not heat enough to vaporize the zinc into the air, all the zinc melts and blends with the copper.

author
bpark1000 (author)Victor8052017-09-12

At its melting point, zinc is volatile! It fumes into the air, then oxidizes to a fine white powder which is readily inhaled.

Workers in zinc smelting factories and brass foundries were known to get "zinc shakes". Campers who grill food on old galvanized refrigerator shelves also get poisoned (unless the shelf is heated red-hot in the fire first to boil off all the zinc).

If you cast brass as a business, the EPA requires zinc-scrubbers on the chimney. The model railroad community has switched to manganese bronze for this reason.

If you do one or a few coins, there is no worry, but it is best to do this outside to be safe.

It is wise to understand the hazards of any operation you perform.

author
Victor805 (author)bpark10002017-09-14

Technically, water is also volatile at it's melting point (0ºC), but the amount of water molecules leaving the liquid state and turning into gas is extremely small. The same applies to zinc. I only heated the coins to 450ºC, which is the maximum temperature my heat gun will output, only 30ºC above zinc's melting point. At that temperature the evaporation rate of zinc is so small it can be considered zero unless this process is done at an industrial scale.

Also there is basically no time for the zinc to evaporate since it instantly bonds with copper creating brass as soon as the melting point is reached.

Firefox_Screenshot_2017-09-14T14-00-37.109Z.png
author
Orngrimm (author)2017-09-14

Ha! Cool idea! :)

author
bolsoncerrado (author)2017-09-12

Thanks for the instructable!

While at high school, we used to clean coins with nitric acid, is that ok with this process too? :)

author
Victor805 (author)bolsoncerrado2017-09-12

Yeah, low concentration nitric acid seems to do wonders cleaning copper. Although for plated coins a less corrosive substance might be preferred.

author
bolsoncerrado (author)Victor8052017-09-12

ty for chimming in ;)

author
AgustinR18 (author)2017-09-10

Serviría para las pistas de un circuito impreso?

author
Victor805 (author)AgustinR182017-09-12

Es muy posible, he pensado lo mismo, pero todas las pistas del circuito deberían de estar interconectadas para que el electrochapado funcione. Quizás se podría chapar una placa entera y luego seguir con el preoceso habitual, así las partes no expuestas tendrían una capa protectora de zinc.

author
HC30 (author)2017-09-10

I just purchased the Medallion Liquid Gold Plating System on eBay for $30, it's quick and safe to use, and will bond pure gold onto real gold, white gold, gold plate, silver, silver plate, platinum, rhodium, nickel brass, bronze, and copper and not just your shiny cooper coins.

author
Victor805 (author)HC302017-09-12

That would be the professional alternative, I'm just doing this for the lulz.

author
deluges (author)2017-09-10

I love it ! I'll try and do it on one a potentiostat at different voltages to see which one works best.

Thanks for sharing

author
MrPapaya (author)deluges2017-09-10

I have lots of brackets and hardware items that are zinc, or at least
zinc plated. Would they work instead of tearing apart a battery?

plate.jpg
author
Victor805 (author)MrPapaya2017-09-12

Maybe, but if they're zinc plated they might not last long and the metal beneath the plating could interfere with the process. I suggest giving it a go just in case.

author
Clasm (author)MrPapaya2017-09-10

If you make sure there isn't some sort of clear coating on it(not likely on a zinc plate, but it never hurts to check), then you should be good to go.

author
photony (author)2017-09-10

I use TABASCO sauce to clean pennies...let a dot sit on a penny for a minute, then blot it...you'll be amazed!

author
Victor805 (author)photony2017-09-12

Lol, tabasco is basically vinegar, salt and red pepper. Good stuff!

author
RoseV5 (author)2017-09-10

Placing the coins on a hotplate is an easy way to get the molecules to blend.

author
Victor805 (author)RoseV52017-09-12

That's also one of the options, it might also be better since you can heat a bunch of coins at a time instead of one by one.

author
jeanniel1 (author)2017-09-10

Cool! What is the photo of the little white balls in the container? The Sodium Hydroxide Where do you get that?

author
Victor805 (author)jeanniel12017-09-12

My local supermarket sells them as drain cleaner in 1kg bottles. If your local supermarket doesn't have it you might find it in a hardware store.

author
bpark1000 (author)2017-09-10

The zinc plate you got from the cell looks like it is from the older acid-based "zinc-carbon" of Laclanche cells. In the newer "alkalline" cells, the zinc is in powder form mixed with copper in the center electrode. Where did you get the cell you stripped the zinc sheet from? Did you get it from a foreign country?

author
Victor805 (author)bpark10002017-09-12

Sorry, I didn't notice. I guess it's an old battery, since it had a carbon rod in the center. The case of that battery is what I used as the zinc plate.

The cell came with a gas water heater, it was used in an electric igniter. It's been sitting for a couple of years in a drawer.

author
InstructableSD (author)bpark10002017-09-10

Zinc carbon batteries are still readily available. They're usually the cheapest batteries you can find and are often labelled heavy duty.

author
ed-romes (author)InstructableSD2017-09-11

Did you consider zinc coated nails ??

author

Thanks! I had the same question!

author
AaronW168 (author)InstructableSD2017-09-10

Yup! Dollar Store Batteries - Preferably Panasonic as I've noticed they contain a bit more 'material' inside compared to the other cheapos. :)

author
KonstantinosE2 (author)2017-09-12

Do the results wear off in time?

author
Victor805 (author)KonstantinosE22017-09-12

The plating resists handling and being in pockets with other items pretty well, although it's not very thick, so deep scratches will reveal the copper beneath. The coins seem stable and don't seem to oxidize when left alone, although if the coin is used regularly it's shininess will decrease as it is scratched and oxidized, like a regular coin.

author
jexy9 (author)2017-09-10

Great instructable. Can I suggest that a zinc anode could be sourced from an outboard motor - they are used as corrosion protection or have a look at item 192221910938 on eBay.

author
marvinmole51 (author)2017-09-10

zinc carbon batteries are the rolled zinc sheet type (many but not all) and are the type that doesn't say "alkaline" or "lithium" on the label... the cheapest type of battery on the shelf.

Tabasco, or indeed most "brown" sauces work because they contain vinegar (acetic acid)

commercial "lime" removing cleaners work very well... in uk and most markets "cillet bang lime and grime" is terrific... spray on (from trigger bottle) and leave 3 minutes and wipe off... or drop into a cup of cleaner from the porable type bottle....

any type of weak acid will work well... but leave the coins too long and the coin will dissolve completely

author
Time_and_Turning (author)2017-09-10

Cool. So with the addition of heat, you're causing the zinc and copper to dissolve into each other creating brass.

I wonder how this process would work with current US coins. Since 1982 with the exception of 2009 the one cent piece (penny) has been copper plated zinc. Since 1965 dimes, quarters, halves and large format dollars have been 'sandwiches': the obverse and reverse sides are layers of cupronickel (75% copper, 25% nickel, traces of manganese) on a pure copper core, which is visible on the edge of the coins. Nickels have been pure cupronickel since 1946. I don't know about more recent dollar coins such as the Susan B. Anthony and Sacajawea. Newer dollars seem to have a shiny or matte yellow surface.

Unfortunately, I will not be able to perform the experiments in the near future.

author
LukeK1990 (author)2017-09-07

Cool instructable! :)

author
Victor805 (author)LukeK19902017-09-08

Thanks!

author
Penolopy Bulnick (author)2017-09-07

This is great! I think I saw this in school once (way back when) but couldn't remember how it was done! Thanks for sharing :)

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Bio: I'm an electronic engineering student. I don't usually have much spare time but I like to work on random projects to keep myself ... More »
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