Also written 鳥子紙. Sometimes abbreviated to torinoko. An eggshell colored, handmade paper *washi 和紙 made from ganpi 雁皮 fibers *ganpishi 雁皮紙 and sometimes with a mix of additional fibers, such as mitsumata 三椏, see *mitsumatagami 三椏紙. Produced in Settsu 摂津 (now Hyōgo Prefecture) and Echizen 越前 (now Fukui Prefecture), see *echizengami 越前紙.
A fine textured, paper with a smooth, glossy surface, making it ideal for kana 仮名 calligraphy. Torinoko means "hen's egg," the color of which is similar to this paper. It evolved in the 14th century, and has been produced in Japan since the late Nara period, when it was known as hishi 斐紙, and was used for copying Buddhist sutra scrolls kyōkan 経巻. During the Heian period it was used for writing collections of waka 和歌 poems.
Torinoko is classified according to its quality, which is related to the quantity of ganpi it contains. The highest class is tokugō 特号, and is made from pure ganpi. Other grades add progressively larger quantities of mitsumata and pulp, which are thought to lower the quality. Untreated torinoko paper absorbs ink, while paper treated with resin during the production process repels ink and has such a high resistant, shiny, beautiful surface, it has earned it the nickname "the king of washi." Thick paper, known simply as torinoko or *atsuyō 厚様, and is used for sliding doors *fusuma 襖, origami 折紙, poem cards *shikishi 色紙 and *tanzaku 短冊, diplomas, and artwork such as calligraphy, drawing, and painting. Thin varieties of torinoko, referred to as gampishi or *usuyō 薄様 are used for preparatory designs and sketches to be reproduced in printing processes. Ganpi produces a strong paper, but it tends to expand or contract according to humidity conditions, making it unsuitable for further processing. For this reason mulberry kōzo 楮 can be added to reinforce the fibers. Torinoko with added kōzo fibers *choshi 楮紙 is known as hankusa-torinoko 半草鳥の子. A version of torinoko made of pulp instead of ganpi is called shin-torinoko 新鳥の子.