Metal soaps critical in speed of deterioration of oil paintings

May 16, 2017, Netherlands Organisation for Scientific Research (NWO)
Metal soaps critical in speed of deterioration of oil paintings
Johannes Vermeer, View of Delft, c. 1660 - 1661. Credit: Mauritshuis, The Hague

An oil painting is not a permanent and unchangeable object, but undergoes a very slow change in the outer and inner structure. Metal soap formation is of great importance. Joen Hermans has managed to recreate the molecular structure of old oil paints: a big step towards better preservation of works of art. He graduated cum laude on Tuesday 9 May at the University of Amsterdam with NWO funding from the Science4Arts program.

Paint can fade, varnish can discolour and paintings can collect dust and dirt. Joen Hermans has examined the chemical processes behind ageing processes in paints. 'While restorers do their best to repair any damages that have occurred, the fact remains that at present we do not know enough about the of ageing oil paint and the chemical processes they undergo', says Hermans. 'This makes it difficult to predict with confidence how paints will react to restoration treatments or to changes in a 's environment.'

Visible to the naked eye

Hermans explains that in its simplest form, oil paint is a mixture of pigment and drying oil, which forms the binding element. Colour pigments are often salts. 'When the pigment and the drying oil are combined, an incredibly complicated chemical process begins', says Hermans, 'which continues for centuries'. The fatty acids in the oil form a polymer network when exposed to oxygen in the air. Meanwhile, metal ions react with the oil on the surface of the grains of pigment.

'A common problem when conserving oil paintings is the formation of what are known as metal soaps', Hermans continues. These are compounds of metal ions and . The formation of metal soaps is linked to various ways in which paint deteriorates, as when it becomes increasingly brittle, transparent or forms a crust on the paint surface. Hermans: 'You can see clumps of metal soap with the naked eye on some paintings, like Rembrandt's Anatomy Lesson of Dr Nicolaes Tulp or Vermeer's View of Delft'. Around 70 per cent of all show signs of metal formation.'

Conserving valuable paintings

Hermans has studied in detail how metal soaps form. He began by defining the structure of metal soaps. One of the things he discovered was that the process that causes to move in the painting is crucial to the speed at which the painting ages. Hermans also managed to recreate the molecular structure of old oil paints, making it possible to simulate and study the behaviour of old paints without actually having to remove samples from Rembrandt's Night Watch. Hermans hopes this knowledge will contribute towards a solid foundation for the conservation of valuable works of art.

Explore further: Video: The weird chemistry threatening masterpiece paintings

More information: Paint Alterations in Time. Implications for Conservation, Presentation and Storage of Oil Paintings from Van Eyck to Mondrian. www.nwo.nl/en/research-and-res … jects/i/59/8159.html

Related Stories

19th century painting tricks revealed

January 9, 2017

To paint quickly while creating exceptional texture and volume effects, J. M. W. Turner and other English artists of his generation relied on the development of innovative gels. All the rage in the 19th century—and still ...

Opening up product design to the consumer through 3-D printing

September 28, 2015

Through the use of 3D printing, product designers can enable the consumer to design their own everyday products thereby creating more meaningful products for people and more value for companies. These are some of the conclusions ...

Liquid hydrogen may be way forward for sustainable air travel

February 23, 2017

Transport makes up around 20 percent of our energy use around the world—and that figure is set to grow, according to the International Energy Agency. With sustainable solutions in mind, a new study published by eminent ...

Green pigment in old masters a myth

March 16, 2005

Old masters never used the green pigment copper resinate supposed to be present in their paintings. Dutch art historian Margriet van Eikema Hommes reached this conclusion on the basis of old paint recipes, investigations ...

Recommended for you

EPA adviser is promoting harmful ideas, scientists say

March 22, 2019

The Trump administration's reliance on industry-funded environmental specialists is again coming under fire, this time by researchers who say that Louis Anthony "Tony" Cox Jr., who leads a key Environmental Protection Agency ...

Coffee-based colloids for direct solar absorption

March 22, 2019

Solar energy is one of the most promising resources to help reduce fossil fuel consumption and mitigate greenhouse gas emissions to power a sustainable future. Devices presently in use to convert solar energy into thermal ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.