How long does a silk pillowcase last?

Silk is strong and durable. There's a reason why good-quality silk can last a lifetime. For a fabric so thin and lightweight, silk is extremely strong. Silk thread is so strong that it's four times tougher than a steel thread of the same thickness. Hundreds of years ago, the Mongolians even made armor out of silk. Silk vests made out of many layers of quilted silk were used to dampen the impact of arrows sinking into the skin. Silk is not only strong but also has great elasticity and excellent resilience. Thanks to these valuable qualities, silk was the fabric of choice for a long time when manufacturing parachutes.