What color is the scroll?

Yellow scroll. In Song Dynasty, Lu You mentioned the color of scrolls in "Jiannan Hakka Poetry", which is an idiom. The yellow scroll is a scroll made of yellow paper. Why is it called yellow scroll? Ancient books were originally copied or engraved on white rice paper because they were often eaten by insects. In order to prevent insects from eating, the ancients often soaked the Chinese medicine Phellodendron amurense juice on paper and then used it to copy or print books. The process of dyeing paper with Phellodendron amurense juice is called yellow (also called yellow dyeing). There is a section in Jia Sixie's Book of Qi Yao Min, which describes in detail the method of dyeing books with phellodendron bark juice. When paper turns yellow, it's called yellow paper, and books made with it are called yellow rolls.