How to know the material of kimono (3) polyester

ポリエステルは簡単だよ！プラスチックみたいなもんだから威勢良く燃えて、燃えたあとは、プラスチックみたいに、固く固くかたまっちまうぜ！ Polyester is often used for the material of washable kimono. It is made of oil, so it burns. If you take off the fire, fire spread rapidly. After extinguish the fire, ash becomes very stiff like plastic!