Make Silver Different Colors by Anodizing

Uploaded by NurdRage on 10.02.2009

Greetings fellow nerds!
In this video we're going to use electrochemistry to add brilliant color
to this otherwise bland and colorless silver bar without using any paint.
This process is called anodizing.
First, we need to make the anodizing solution.
We start with about half a cup of water
and add two tablespoons of sodium hydroxide and one tablespoon of sulfur.
Both of these chemicals are easily bought online.
Then we stir for about ten minutes,
which we'll timelapse for this video.
At the end we get this orange solution of sulfur and sodium hydroxide
which is highly corrosive so always wear gloves when working with it.
Next we filter the anodizing solution to remove any excess sulfur.
You can use a coffee filter for this process.
Now we have our anodizing solution ready to color our silver bar.
Here is our brand new silver bar.
Place the silver bar into the solution.
Next you'll need a battery to generate the anodizing potential.
Now connect the positive terminal of the battery to the silver piece and when you're ready,
touch the negative wire to the surface of the solution but NOT to the actual silver piece.
As you can see it doesn't take much time to start adding color to the bar.
Ok let me take it out and show you what we have.
I'm going to wash it for a better look.
As you can see, in just a few seconds we've added decades of tarnish to the bar
and turned it a brown color with blue highlights.
If we keep going, we can continue changing its color.
So let's do that.
Looks like we've got some sort of green blue color this time.
Let me give it a rinse.
As you can see,
the length of time it takes to anodize determines the color of the silver.
Let's go on for a few more seconds and see what happens.
I move the negative wire around the bar to give it an even coat.
Otherwise the part closest to the wire will anodize faster than the rest.
Looks like we got some kind of dull grey color now.
Ok another round.
I'm not certain how to describe this one, a blue purple color?
Ok once we get to this matte black color further anodizing will no longer give us a color change.
Now I said before I needed to move the wires
because the part closest to the wires will anodize faster than the rest.
So what happens if I don't move them?
Let's find out with this new silver bar.
As you can see we've gotten this rainbow effect
as the parts closest to the wire change color more than the farthest parts.
Pretty cool eh?
Thanks for watching another NurdRage original video.