The Slow Blade Penetrates the Shield

How Liquid Body Armor Works (excerpt + link)

by Tracy V. Wilson for howstuffworks.com

The basic idea behind body armor hasn't changed very much in the past few thousand years. First, armor stops weapons or projectiles from reaching a person's body. Second, it diffuses the weapon's energy so that the final impact causes less damage. While it's not effective in every situation, armor can generally help protect people from serious injury or death, especially against the right weaponry.

Over the years, people have had to develop stronger and more advanced armor to protect against increasingly sophisticated weapons. However, in spite of these improvements, modern body armor still has some of the same shortcomings as ancient forms of armor. Whether it's made from metal plates or layers of fabric, armor is often heavy and bulky. Many types are rigid, so they're impractical for use on arms, legs and necks. For this reason, medieval suits of plate armor had gaps and joints to allow people to move around, and the body armor used today often protects only the head and torso. Continued here.