Washi is the light, strong traditional Japanese paper made by hand from the inner-bark fibers of three plants. The name washi literally means "Japanese paper". Today most paper in Japan is made in large automated mills, but a few hundred families in rural villages continue to make washi in the traditional way.
Traditionally, Japanese farmers make paper in the winter after all of the other crops have been harvested. The cold temperatures keep the organic materials fresh. The fibers in the pulp also contract in the cold weather and form a stronger sheet of paper.
Since paper is essentially a combination of vegetable fibers and water, pure cold water is also vital to the art of making washi. Any minerals or impurities in the water will eventually mar the paper. The final ingredient in high quality paper is, of course, the fibers that are used. The three fibers used to create washi are kozo, gampi and mitsumata.