This paper analyses the possible effect of residual drying stresses on the permanent deformation of panel paintings. For this purpose, experiments were done, during which samples were submitted to several adsorption–desorption cycles to reproduce what could happen in real climatic conditions. The painted side is regarded in this work as a sealed surface that is mimicked by insulated some faces of the sample with an aluminium sheet. The asymmetry of the moisture content profile generates a global curving of the sample section that is followed over time. Results show that humidity variations in the surrounding, because acting on one single face, reduce the residual drying stress by activating the mechano-sorptive creep. This effect gives rise to a concave cupping towards the non-painted face. This deformation does not disappear as the moisture content becomes uniform across the panel.