Ferrer, S;
Campo-Francés, G;
Grau-Bové, J;
Bautista-Morenilla, I;
Nualart-Torroja, A;
(2022)
RH simulation model for canvas paintings protected by an aluminium backplate and an additional hygroscopic layer.
Heritage Science
, 10
(1)
, Article 115. 10.1186/s40494-022-00741-2.
(In press).
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Abstract
To protect a canvas easel painting, a common conservation strategy is to add a back plate at the stretcher, creating a closed air void. This plate protects not only from dust but mainly from temperature and relative humidity (RH) variations in the room and moisture changes in the wall on which it is hanging. The addition of hygroscopic layers can reduce the amplitude and change phase of humidity oscillations. This paper proposes a new mathematical model that can be used to predict moisture levels within the canvas when this conservation strategy is applied. The model is compared against the temperature and RH detailed experimental data, captured and shown in the latest paper by Padfield et al. Back protection of canvas painting. Our paper presents values of T, RH and mixing ratio (MR) obtained at the different layers of an easel painting, protected and unprotected, with cotton and without it, submitted to different room and wall temperature and RH cycles. The experimental results show a phase displacement between the canvas temperatures and the corresponding RH values in the canvas air boundary layer. In some cases this phase shift, which is an unexpected behaviour, allows RH and temperatures to achieve their maximum value at the same time. The purpose of the model is to simulate the RH response at the different air boundary layers inside the air void, such as the canvas, the aluminium back plate, and the hygroscopic cotton protection, produced by cyclic variations of temperature in the room or the wall. The model is built simulating four interrelated processes: the canvas permeation flow, the air infiltration rate between room and void, the equilibrium moisture content (EMC) and the vapour sorption rate for the canvas and the cotton. A key innovation of the model is the dependence between EMC, sorption rate, and RH condition, which captures the counter-intuitive behaviours observed in the data. The model results agree with the experimental results. The developed tool allows the interpretation of the processes involved and to extend the simulations to other cases, materials, and conditions.
| Type: | Article |
|---|---|
| Title: | RH simulation model for canvas paintings protected by an aluminium backplate and an additional hygroscopic layer |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1186/s40494-022-00741-2 |
| Publisher version: | https://doi.org/10.1186/s40494-022-00741-2 |
| Language: | English |
| Additional information: | Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. |
| Keywords: | Painting conservation, Canvas protections simulation, Canvas permeation, Linen sorption, Cotton sorption, EMC |
| UCL classification: | UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of the Built Environment UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of the Built Environment > Bartlett School Env, Energy and Resources UCL > Provost and Vice Provost Offices > UCL BEAMS UCL |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10157386 |
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