The Science of Beautiful Easter Egg Color

[Narrator] If you celebrate Easter,

you'll probably be dying some eggs.

Here's what science has to say

about making them look brilliant.

To start, most food dyes only work in acid, like vinegar,

which is five per cent acetic acid.

We wanted to know exactly what pH

gets you the best saturation.

So we tested six different conditions along the pH scale.

From pure water at pH seven,

to pure vinegar at pH three.

The color saturation depends on the bond

between the shell surface

and the dye's molecules.

Pure water barely activates the acid dye.

Pure vinegar makes for more vibrant colors,

but there's a hitch.

See that bubbling?

That's free protons from the acid

reacting with the shell's calcium carbonate

creating CO2 bubbles that can leave you with a blotchy egg.

We found that for bright, well-bonded colors,

the ideal pH is four.

Of course you could use other edible acids,

like lemon juice,

but there's something about the whiff of vinegar

that just says spring.