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

TL;DR

This paper investigates the causes of Qi-Wa, the curling of Chinese scrolls, revealing that intrinsic curvature from storage is the main factor, and proposes remedies supported by experiments, simulations, and theoretical analysis.

Contribution

It identifies the primary cause of Qi-Wa as intrinsic curvature from storage and develops scaling relations and remedies validated through experiments and simulations.

Findings

Qi-Wa height scales with scroll dimensions and curvature.

Intrinsic storage curvature is the main cause of Qi-Wa.

Proposed remedies effectively reduce Qi-Wa in experiments.

Abstract

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.