My wife recently stumbled upon an exciting family heirloom, an ancient metal cup that was engraved with what appeared to be her father’s name and birth date. The problem was that this silver treasure was nastily tarnished inside and out. The engraving couldn’t be read and you’d not dare drink anything out of this cup. What happened next is exactly what you might expect when you’ve got a science obsessed daughter in your midst — a fun science activity to make the tarnish and rust disappear!
If you have a vintage piece of rusty metal from yesteryear in your home or want to pick up an inexpensive little something at an antique shop, here’s the simplest, cheapest and most enjoyable way to make the rust or tarnish disappear and restore glory to your treasure.
What You’ll Need
- Some piece of tarnished or lightly rusty metal
- Baking soda
- Warm water
- Aluminum Foil
How to Make Rust Disappear
- Line your bowl with aluminum foil.
- Fill up the bowl with boiling water and pour in some baking soda.
- Submerge the once-and-future shiny metal object and wait.
- Wait some more.
- A bit more waiting…
- Hold on…
- (at this point, a few hours have gone by)
- Okay, now!
- Take out the object and gently scrub off the tarnish or rust with a toothbrush you don’t want to use on your teeth ever again. You want to do this gently because baking soda is abrasive and you wouldn’t want to be too harsh and scratch the ancient metal treasure you are attempting to restore to its prior glory!
- The tarnish and rust should come off with ease, if it does not, add more baking soda then back into the bath it goes for a little while longer, and repeat step #9 or see below for battling extreme rust.
In extreme cases of rust, work in a small batch to mix warm water and baking soda until you’ve made a thick paste, then apply directly to the rust and scrub with some vigor to clean.
Here’s the science behind why warm water, aluminum foil and baking soda make rust and tarnish disappear from silver, from University of Wisconsin-Madison Chemistry Professor Bassam Z. Shakhashiri: “When silver tarnishes, it combines with sulfur and forms silver sulfide, which is black. When a thin coating of silver sulfide forms on the surface of silver, it darkens the silver but can be returned to its former luster by removing the silver sulfide coating from the surface [with this simple activity and regular materials most families have already in their home]”
“The reaction between silver sulfide and aluminum takes place when the two are in contact while they are immersed in a baking soda solution. The reaction is faster when the solution is warm. The [baking soda and warm water] solution carries the sulfur from the silver to the aluminum foil!”