Date Uploaded: April 11, 2004, 7:37 pm
Last Edited: December 7, 2012, 9:49 pm
(Zinc) and Brass Pennies
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(Zinc) and Brass Pennies
Article © MAIL User: Drax
You may have seen this demonstration in chemistry lab, if not, you're in for a real treat. The recipes below will help you turn pennies into a silver color by plating them in zinc, and also finally turn them into brass!
I write this information for you use because pennies have found their way into some chainmaille uses (pennymaille), and so now you can incorporate different colors! If you are going to use these altered pennies for pennymaille, I recommend doing the change after you punch holes in them.
A common question is, aren't you illegally defacing currency?
Check out: Defacing Currency
Most chemistry labs recommend using pre-1983 pennies for this lab, however I found that you get much prettier pennies out of post-1983 pennies. I'm not sure if this is because they're generally newer and shinier, or if it's because of the difference in composition. Before 1983 (or 1985?) pennies were mostly made of copper. Post-1983 pennies are almost all zinc, with a copper coating.
The basic idea of the procedure is to plate zinc onto the surface of the penny (giving it the silver color), then heating it to mingle the copper and zinc to form brass. See the picture toward the end of this article.
That's why most directions recommend using pre-1983 pennies -- to ensure you get enough copper. But I think you're find using post-1983 pennies, especially since you can get them very new, and already very shiny.
What you'll need:
1. Vinegar, or lemon juice, or muriatic acid (hydrochloric acid)
(only if your pennies are dark)
2. Zinc dust
3. Lye (sodium hydroxide, 3M solution)
4. Heat source -- bunsen burner, zippo? oven?
Make sure the pennies are clean. They should be shiny and have an almost orange-pink color (not the typical dark brown). Scrub the pennies to remove any junk, and then dunk them in either the vinegar, lemon juice of hydrochloric acid to clean the surface and expose fresh copper. Be careful when handling the chemicals. Rinse multiple times with fresh water and try not to touch, since your finger oils can mar the surface.
Prepare a solution of 25 mLs of 3M sodium hydroxide and place in it 1 gram of zinc dust (be careful of the zinc dust, inhaling it can cause the 'zinc shakes', a flu-like response). Heat this solution to *steaming*, not boiling (you'll begin to see water vapor readily rise up from the surface, but it won't be bubbling). Place your cleaned pennies into this solution. You can stir it around if you like, but they should rest in there for around 3 minutes or so.
Pull a penny out -- it should be coated in zinc and have a silver color. If it has adequate coverage (it should look entirely silver), then it's done. If you can still see some copper color, put it back for more time. Take the pennies out when done, swish in clean water and rub any excess dust clinging on the surface till they are nice and shiny silver. You can stop here if you desire silver-colored pennies.
If you want brass pennies, place a zinc-coated penny in some tweezers (I usually hold by the rim of the coin) and pass it through the flame of a bunsen burner (a zippo, torch, or oven might work, but you'll have to be very careful). Try to do this in a well-ventilated area, and do NOT breathe any fumes that come from the penny (again, you risk exposure to breathing zinc fumes). Within about 5-10 seconds, the coin should turn yellow-gold. Hold it in the flame a couple seconds more, then plunge it into cool, clean water. It'll come out bright and brassy! Dry it off and give it a good polish. Enjoy showing your friends, too, it's pretty nifty (and it's real brass).
Take a look at the following picture:
On the left are the pre-1983 pennies, and on the right are the post-1983 pennies. The top row is an uncleaned, normal penny. The second row shows the zinc-coated pennies. The third row shows the brass pennies. The last row shows what happens if you try to take a post-1983 penny and heat it directly without any chemicals (since it's mostly zinc with a copper coating) -- they don't turn out too well that way.
As always, please be careful when using chemicals of this nature. Almost all of them can be very dangerous.
Enjoy, it's a lot of fun, and a great way to add color to your pennymaille...
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