Paper detail

Qi-Wa, a problem that has plagued Chinese scrolls for millenniums

Qi-Wa refers to the up curl on the lengths of handscrolls and hanging scrolls, which has troubled Chinese artisans and emperors for as long as the art of painting and calligraphy exists. This warp is unwelcomed not only for aesthetic reasons, but its potential damage to the fiber and ink. Although it is generally treated as a part of the cockling and curling due to climate, mounting procedures, and conservation conditions, we emphasize that the intrinsic curvature incurred from the storage is in fact the main cause of Qi-Wa. The Qi-Wa height is determined by experiments to obey scaling relations with the length, width, curvature, and thickness of the scroll, which are supported by Molecular Dynamics Simulation and theoretic derivations. This understanding helps us come up with plausible remedies to mitigate Qi-Wa. All proposals are tested on real mounted paper and in simulations. Due to the general nature of this warp, we believe the lessons learnt from studying ancient Chinese scrolls can be applied to modern technologies such as the development of flexible electronic paper and computer screen.