Why put car keys in aluminum foil?

What Is a Faraday Cage (In Simple Terms)?

A Faraday cage is an enclosure made of conductive material that blocks electromagnetic signals.

You don’t need a laboratory version. Even simple materials—like aluminum foil—can reduce signal transmission when used correctly.

That’s why:

• Elevators lose phone signal
• Microwave ovens have metal mesh
• Shielded cables resist interference

Wrapping keys in foil creates a basic shield.

Does Aluminum Foil Actually Work?

Yes—to a degree.

Aluminum foil can:

• Reduce or block key fob signals
• Prevent relay amplification
• Add a layer of protection

However, it is:

• Not perfect
• Not stylish
• Not a permanent solution

It’s best seen as a temporary or emergency measure.