And now one more word about armor, using a material you might not expect: silk. Silk is stronger than you might think, maybe even strong enough to make body armor that protects against bullets. Bullet-resistant vests are now made from Kevlar, which is a synthetic fiber.</s>RENEE MONTAGNE, host: Using silk as the raw ingredient could make those vests more comfortable, lighter to wear, and maybe even tougher. Here's David Kaplan, a professor in the Department of Biomedical Engineering at Tufts University, speaking about silk's charms on NPR's SCIENCE FRIDAY.</s>Professor DAVID KAPLAN (Tufts University): Silk is very, very strong if you pull on it, but it's also very, very strong and durable if you squish it or compress it. And that's where it's quite distinguished from the Kevlar, which is strong when you pull on it but if you squish it, it doesn't perform as well. And so these combinations of properties give rise to the interest in making things like protective vests and other equipment. And down the road I anticipate we'll see much of this.</s>RENEE MONTAGNE, host: Professor Kaplan also points out that silk has been used for making protective gear for millennia.</s>Professor DAVID KAPLAN (Tufts University): Historically, if you look back in museums in Japan and China, you'll find armor was made of silk, you know, thousands of years ago for the same reasons, because of the real toughness of this fiber.</s>RENEE MONTAGNE, host: An ancient use for silk, possibly new again. Tufts University engineering professor David Kaplan is an author of an article on the amazing properties of silk in the current issue of the journal Science.
Bullet-resistant vests are made from Kevlar, a synthetic fiber. But using silk as the raw ingredient could make them more comfortable, lighter to wear and maybe even tougher.