It homogenized the metal within the layers, spreading the elements (such as carbon) evenly throughout the individual layers, increasing the effective strength by decreasing the number of potential weak points. It burned off many impurities, helping to overcome the poor quality of the raw Japanese steel. It created up to 65,000 layers, by continuously decarburizing the surface and bringing it into the blade's interior, which gives the swords their grain (for comparison see pattern welding).