Modern Paint Damage Atlas
 
 

Degradation phenomena


water sensitivity

Causes of Water Sensitivity in Acrylic Paint
Acrylic paints have been popular with artists since their invention after the second World War. Their ability to be used with extreme flexibility, from transparent washes or ‘stains’ to thick, heavy bodied paint, excited artists and lead to visual effects previously not possible with traditional media. From a conservators point of view, acrylic paint tends to be more flexible and has less cracking than traditional (stiff, brittle) oil paint. Acrylic paintings also often tend to be large, durable but simultaneously fragile works (Doménech Carbó M.T. et al. 2013, Stavroudis et al. 2013).

Water and solvent sensitivity in acrylic and acrylic emulsion paint is a well-known phenomenon that has been studied extensively. Like oil paints acrylic paints have a tendency to form a ‘skin’ or film on the surface as it dries and hardens. The two main ways in which water and solvents affect an acrylic paint film is by swelling the film and extraction of paint film components. These can lead to various changes in the appearance of the paint, including changes to colour, gloss and adhesion (Wolbers et al. 2013, Jablonski et al. 2003, Jablonski et al. 2010).

A number of different factors can influence the extent to which an acrylic paint film can be affected by water or other solvents. The concentration of pigment, added fillers, age hardening at the surface, polymer elasticity, film drying rate, film thickness, prior treatments and environmental factors (such as Relative Humidity, temperature and environmental conditions) all affect the aging properties of an acrylic film, and by extension its swelling and extraction properties (Wolbers et al. 2013). Surfactants are added as stabilizers and pigment wetting agents to acrylic and acrylic dispersion paints. They are often found to be concentrated on the surface of acrylic paint films, having migrated from the bulk of the paint, although they are also found in the bulk of the paint film too. These surface surfactants can be degraded by light, and can have various optical effects on the paint layer, from matte spots to a mottled effect or the appearance of a surface haze over a section or entire paint film (Ormsby et al. 2009, Ormsby et al. 2013).
Acrylic paint films have a low Glass Transition temperature (Tg) at ambient temperatures, which is caused by surfactants acting as a plasticiser to the paint film. A low Tg indicates a softness of the paint, and combined with the separation and migration of surfactants to the surface of the paint films, acrylic paints are particularly vulnerable to dirt attraction, which becomes imbibed in the surface. Often finger marks and scuffs from handling are found in their surfaces, along with accumulated surface and imbibed grime (Stavroudis et al. 2013).

Treatment of Acrylic Paintings
As mentioned, the two ways in which water and other solvents affect paint films is by swelling of the film and the leaching of components. These processes often occur simultaneously.

Swelling by water and (hydrocarbon) solvents can occur at macro and micro scale. Exposure to water can leave surfaces with increases of pores or perforations, surface erosion, roughness or scratches. Cleaning with low polar solvents can lead to the solubilisation of polymer chains and additives in the paint film, leaving it more brittle and sensitive (Wolbers et al. 2013).

The leaching of components such as surfactants from the paint film will leave the paint film more brittle. The migration of surfactants to the surface is exacerbated by aqueous cleaning, and may actually risk embedding the dirt or soiling more thoroughly by solubilising the film and then leaving it to harden (Doménech Carbó M.T. et al. 2013).

As dirt is often imbibed or well-adhered to acrylic paint films, dry cleaning methods are not always effective, and can leave their own specific types of damage on these films (residues, changes to surface gloss, streakiness, for example). This means that, despite the risks, ‘wet’ solutions such as aqueous systems or those based on solvents are required to remove dirt. Aqueous solutions are known to have the greatest effect for the removal of surface dirt (Ormsby et al. 2009).

The use of deionised water, as is often used for old oil paint films, draws out film materials, like surfactants, as it is a hypotonic solution. Hypertonic solutions, on the other hand, with high conductivity, are less likely to draw out materials or swell the films (Wolbers et al. 2013, Dillon et al. 2012). Solutions with a high pH (of around 4-5) are also recommended for dirt removal, leaving the paint film intact. The ionic strength of a film has also been shown to be of importance, with Stavroudis (2013) recommending around 29 mM concentration. He recommends using carbonated distilled water, which naturally has a pH of around 6.3 with the addition of 1% of ethanol as this lowers the effective detergency of the cleaning solution. The use of gels, for example Agar, is also recommended for the removal of surface dirt from acrylic paintings, as is the use of a micro-aspirator (Cremonesi 2016, Ormsby et al. 2009, Ormsby et al. 2013, Lagalante et al. 2016, Stavroudis et al. 2013).


Causes & treatment of ...

>> Water Sensitivity in Oil Paint

literature
Water Sensitivity in Oil Paint

Anzani M. et al., Gel rigidi di Agar per il trattamento di pulitura di manufatti in gesso. Use of rigid agar gels for cleaning plaster objects, 2008, in: CESMAR 7 (Quaderno 6),

Banti D., La Nasa J., Tenorio A., Modugno F., van den Berg K.J., Lee J., Ormsby B., Burnstock A., Bonaduce I., A molecular study of modern oil paintings: Investigating the role of dicarboxylic acids in the water sensitivity of modern oil paints, 2018, in: RSC Advances vol. 8 issue 11 (2018), pp 6001-6012

Bonaduce I., Carlyle L., Colombini M.P., Duce C., Ferrari C., Ribechini E., Tiné M.R., New insights into the Aging of Linseed Oil Paint Binder: A Qualitative and Quantitative Analytical study, 2012, in: PLOS ONE vol. 7 nr 11,

Burnstock A., Bay L., Lee J., Ormsby B., van den Berg K.J., Water sensitivity of modern oil paintings, 2017, in: Postprints of the ICOM-CC 18th Triennial Conference, Copenhagen, 2017, paper 1302
https://www.icom-cc-publications-online.org/PublicationDetail.aspx?cid=c25759cc-4481-4b30-b785-03a57a3a47f9

Burnstock A., van den Berg KJ., De Groot S., Wijnberg L., An investigation of water-sensitive oil paints in the 20th Century paintings, 2007, in: Modern Paints Uncovered. The Getty Conservation Institute, Los Angeles, pp 177-188

Campani E, L’uso di agarosio e agar per la preparazione di ‘gel rigidi’. Use of agarose and agar for preparing ‘rigid gels’, 2006, in: CESMAR 7 (Quaderno 4), pp 205-207

Chung J.Y., Ormsby B., Lee J., Burnstock A., van den Berg K.J., An investigation of options for surface cleaning unvarnished water-sensitive oil paints based on recent developments for acrylic paints, 2017, in: Postprints of the ICOM-CC 18th Triennial Conference, Copenhagen, 2017, paper 1309
https://www.icom-cc-publications-online.org/PublicationDetail.aspx?cid=a83b8857-a4d6-41d3-b00d-5f7a23eb3d4d

Cooper A., Burnstock A., van den Berg K.J., Ormsby B., Water sensitive oil paints in the twentieth century: a study of the distribution of water-soluble degradation products in modern oil paint films, 2014, in: Issues in Contemporary oil paint, pp 295-310

Cremonesi P., Surface cleaning? Yes, freshly grated Agar gel, please, 2016, in: Studies in Conservation vol.61, 2016, issue 6, pp 362-367

Daudin-Schotte M., Bisschoff M., Joosten I., Keulen H., van den Berg K.J., Dry cleaning approaches for unvarnished paint surfaces, 2013, in: New Insights into the cleaning of paintings. Proceedings from the cleaning 2010 international conference Universidad Politécnica de Valencia and Museum Conservation Institute. Smithsonian Institution Scholarly Press, Washington DC, pp 209-219

Finozzi A. et al., The use of agar cyclododecane for cleaning tests on a frail painting, 2013, in: New Insights into the cleaning of paintings. Proceedings from the cleaning 2010 international conference Universidad Politécnica de Valencia and Museum Conservation Institute. Smithsonian Institution Scholarly Press, Washington DC, pp 407-417

Hartman D., Wingel K., Nigro E.M., Porell M., Teeter K., New applications of Pickering-type emulsions for the cleaning of modern water-dispersed oil paints, 2017, in: Postprints of the ICOM-CC 18th Triennial Conference, Copenhagen, 2017, paper 0915
https://www.icom-cc-publications-online.org/PublicationDetail.aspx?cid=3bc4c660-1030-4116-80fb-9c9bf062dba0

Izzo F.C., van den Berg K.J., van Keulen H., Ferriani B., Zendri E., Modern oil paints- Formulations, organic additives and degradation: some case studies, 2014, in: Issues in Contemporary Oil Paint, pp 75-104

Keune K. and Boevé-Jones G. , Its Surreal: Zinc-Oxide Degradation and Misperceptions in Salvador Dalí’s Couple with Clouds in Their Heads, 1936, 2014, in: Issues in Contemporary Oil Paint, pp 283-294

Lee J., Ormsby B., van den Berg K.J., Burnstock A., Chemical characterisation of the organic fraction of water-sensitive Winsor & Newton paint swatches and selected modern oil paintings, 2017, in: Postprints of the ICOM-CC 18th Triennial Conference, Copenhagen, 2017, paper 1604

Lee, J., Bonaduce I., Modugno F., La Nasa J., Ormsby B., Van den Berg K.J., Scientific investigation into the water sensitivity of twentieth century oil paints, 2018, in: Microchemical Journal, vol. 138, May 2018, pp 282-295

Mills L., Burnstock A., Duarte F., van Keulen H., Megens L., van den Berg K.J., Water sensitivity of modern artists’ oil paints, 2008, in: ICOM Committee for Conservation (ICOM-CC) 15th Triennial Meeting New Delhi, 22-26 Sept 2008, pp 651-659

Ormsby B., Learner T., Recent Developments in the cleaning of modern paints, 2016, in: Conservation Perspectives, Fall 2016, Conserving Modern Paints, The Getty Conservation Institute,
http://www.getty.edu/conservation/publications_resources/newsletters/31_2/feature.html

Paviç M., Non-traditionally painting oil painting: how to treat it properly? Josip Vaništa's Cakes (1955), 2014, in: Issues in Contemporary oil paint, pp159-166

Pratali E., Zinc oxide grounds in 19th and 20th century oil paintings and their role in picture degradation processes, 2013, in: CeROArt vol.3, pp 1-22
https://doi.org/http://ceroart.revues.org/3207

Sanchez-Ledesma A. et al., Effects of commercial soaps on unvarnished painted surfaces: A pilot study for their assessment, 2013, in: New Insights into the cleaning of paintings. Proceedings from the cleaning 2010 international conference Universidad Politécnica de Valencia and Museum Conservation Institute. Smithsonian Institution Scholarly Press, Washington DC, pp 52-62

Silvester G., Burnstock A., Megens L., Learner T., Chiari G., Van den Berg K.J., A cause of water-sensitivity in modern oil paint films: the formation of magnesium sulphate, 2014, in: Studies in Conservation, 59 (1), pp 38-51

Soldano A., Van den Berg K.J., Investigation into the surface conductivity of water-sensitive modern oil paints, 2014, in: Issues in Contemporary oil paint, pp 185-196

Stavroudis C., Silicone Based solvents in Conservation- As free solvents and components of gel systems and microemulsions, 2016, in: Colore e Conservazione, 13–14 November 2015, Politecnico di Milano. Padova, pp 176-184

Steyn L., Stols-Witlox M., Hendriks E., van den Berg K.J., Cleaning modern oil paints: The removal of imbibed surface dirt. Towards an integrated conservation methodology for the assessment, contextualization and treatment of imbibed surface dirt on unvarnished modern oil paintings, 2017, in: Postprints of the ICOM-CC 18th Triennial Conference, Copenhagen, 2017, paper 1317

Tempest H., Burnstock A., Saltmarsh P., van den Berg KJ., Sensitivity of oil paint surfaces to Aqueous and other solvents. Progress in the water sensitive oil project, 2013, in: New Insights into the cleaning of paintings. Proceedings from the cleaning 2010 international conference Universidad Politécnica de Valencia and Museum Conservation Institute. Smithsonian Institution Scholarly Press, Washington DC, pp 107-117

Tempest H., Burnstock A., Saltmarsh P., van den Berg KJ., Sensitivity of oil paint surfaces to aqueous and other solvents, 2013, in: New Insights into the cleaning of paintings. Proceedings from the cleaning 2010 international conference Universidad Politécnica de Valencia and Museum Conservation Institute. Smithsonian Institution Scholarly Press, Washington DC, pp 107-117
https://repository.si.edu/bitstream/handle/10088/20496/18.Tempest.SCMC3.Mecklenburg.Web.pdf?sequence=1&isAllowed=y

Tumosa C.S., A brief history of Aluminium Stearate as a component of paint, 2001, in: WAAC Newsletter vol. 23 issue 3,

Tumosa C.S., Meklenburg M.F., The influence of lead ions on the drying of oils, 2005, in: Studies in Conservation vol. 50, sup 1., pp 39-47

Van den Berg K.J., Notes on metal soap extenders in modern oil paints - history, use, degradation and analysis, 2017, in: Metal Soaps in Art – Conservation & Research. New York: Springer.,