RH simulation model for canvas paintings protected by an aluminium backplate and an additional hygroscopic layer

Abstract To protect a canvas easel painting, common conservation strategy is to add back plate at the stretcher, creating closed air void. This protects not only from dust but mainly temperature and relative humidity ( RH ) variations in room moisture changes wall on which it hanging. The addition of hygroscopic layers can reduce amplitude change phase oscillations. paper proposes new mathematical model that be used predict levels within when this applied. compared against detailed experimental data, captured shown latest by Padfield et al. Back protection painting . Our presents values T, mixing ratio MR obtained different an protected unprotected, with cotton without it, submitted cycles. results show displacement between temperatures corresponding boundary layer. In some cases shift, unexpected behaviour, allows achieve their maximum value same time. purpose simulate response inside void, such as canvas, aluminium plate, protection, produced cyclic or wall. built simulating four interrelated processes: permeation flow, infiltration rate equilibrium content EMC vapour sorption for cotton. A key innovation dependence EMC, rate, condition, captures counter-intuitive behaviours observed data. agree results. developed tool interpretation processes involved extend simulations other cases, materials, conditions.