Sadaijin (minister of the left), FUJIWARA no Yorinaga was famous as a book collector and his book storerooms were said to have been strengthened by applying caustic lime or oyster shell to their wood walls.
なお、蔵書家として名高い平安時代の左大臣藤原頼長の書庫ですら、板壁の上に石灰や蠣殻を塗って補強したものであったとされる。