Silk and the Samurai's Sword might be different from each other, but they have something in common. They both have gone through a chemical change. Silk is a modern day wonder while the Samurai Sword has been used for centuries.
The chemical change that silk has gone through is water turning into a protein fiber. This happens when the silk solution sets at room temperature and letting the protein fibers assemble by themselves. Next the solution is boiled, then the protein fibers are detach while the water is evaporating. This process makes silk. The silk can now be used for various things, for example to create gears, bolts and senors. Silk is also biocompatible. This means that it can be implanted into the body with no harm done to the living tissue.
The chemical change that the Samurai's Sword has gone through is the mixing of iron and charcoal to create steel. This happens when iron and charcoal are heated together in a tatara for 3 nights and days. After the steel has been heated it is separated into two groups, high carbon and low carbon. The high carbon is used for the razor shape edge of the sword, while the low carbon is tough and allows for shock absorption. A blacksmith will then shape the high carbon steel so that the low carbon may be able to fit in the high carbon steel. This allows for the perfect balance of properties which is the samurai's most durable and prized weapon (taken from http://www.pbs.org/wgbh/nova/tech/crafting-samurai-sword.html, 1/26/12). To make the distinctive curve on the sword, the sword is then heated again to 1,500 degrees Fahrenheit . After that the sword is placed into a shallow container of water to cool. The speed of the contraction in the water between the low and high carbon causes it to bend. Thus creating the Samurai's Sword
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