Cleaning Modern Oil Paints Project

Tate is the newest recipient of the NHSF Gold Open Access grant for the publication of heritage science research. The grant enabled the publication of the research paper Scientific investigation into the water sensitivity of twentieth century oil paints’, available for free in Microchemical Journal. In this guest post, the paper’s authors tell us more about the Cleaning Modern Oil Paints project.

The Cleaning Modern Oil Paints project (CMOP) is a collaborative European research project, funded through the JPI Heritage Plus programme, which runs from June 2015 – May 2018. The project aims to investigate conservation challenges associated with twentieth and twenty-first century oil paintings in order to ensure that modern oil paintings continue to be fit for display for future generations.

Many unvarnished twentieth and twenty-first century oil paintings are exhibiting unusual water sensitivity. Water sensitivity can be defined as the unwanted removal of pigment and/or original material when a discrete cleaning test is carried out using a dampened cotton swab on the surface of a painting. Water sensitivity is not restricted to a particular oil-paint brand, or artist, and affects a broad range of paintings.

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Winsor & Newton Artist Oil Colour swatches that were studied as part of the microchemical journal paper. Copyright Tate.

Water sensitivity is problematic for conservators, since many of the well-established methods for removing surface dirt (which naturally gathers over time) involves the skilled application of water based cleaning systems.  Since dry-cleaning methods, for example using dry brushes or specialist sponges, are not always particularly effective at removing soiling, water sensitivity can complicate or even prevent effective treatment. This is problematic as accumulated surface dirt can change the appearance of paintings e.g. through altering the saturation, intensity and gloss of paint passages, and can, over the longer term, contribute to other unwanted side-effects relating to ageing and deterioration.

The interdisciplinary CMOP team have been investigating the underlying causes of water sensitivity in modern oil paints. This information has been used to inform the systematic testing and evaluation of selected cleaning systems for use on water sensitive modern oil paintings, with the aim of informing conservators about the risks involved and how to minimise them.

Part of the CMOP research has involved the chemical analysis of a series of naturally aged modern oil paint micro-samples, taken from case study oil paintings and from historic Winsor & Newton (W&N) artists’ oil paint swatches.  The W&N paint swatches were originally produced by the manufacturer for quality control testing, and were subsequently donated to Tate by ColArt UK for research purposes.

W&W Artist Oil Colour swatches studied for the paper, shown in tungsten light (left) and UV light (right). Copyright Tate.

We are pleased to announce that the National Heritage Science Forum has kindly sponsored the Gold Open Access publication of a key CMOP research paper, entitled Scientific investigation into the water sensitivity of twentieth century oil paints, now published in the peer-reviewed Microchemical Journal. This describes an in-depth investigation into the chemical characteristics of water sensitive paint passages, and likely causal factors.

The research at Tate is led by Principal Conservation Scientist Dr Bronwyn Ormsby, with Post-doctoral Researcher Judith Lee, and with the support of Tate’s Collection Care Research. More information on the project and details of the key CMOP project dissemination event; Conference on Modern Oil Paints taking place on 23-25 May 2018, are available on Tate’s website.

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Detail of a case study oil painting analysed as part of the project. Copyright Tate.

 

The paper Scientific investigation into the water sensitivity of twentieth century oil paints is co-authored by Judith Lee and Bronwyn Ormsby of the Tate Conservation Department, Ilaria Bonaduce, Francesca Modugno, Jacopo La Nasa and Klaas Jan van den Berg.

The National Heritage Science Forum provides Gold Open Access grants to help to open up access to heritage science research. This funding is available to employees, students and members of our member organisations – find out more.

Advanced imaging technologies uncover hidden details on Rubens paintings

Next in our British Science Week 2018 series, Historic Royal Palaces’ Senior Conservation Scientist Dr Constantina Vlachou-Mogire tells us about investigating the Rubens ceiling paintings at Banqueting House…

Historic Royal Palaces is preparing for the 400th anniversary of the Banqueting House, which will take place in 2022. During this major project we have a rare opportunity to access and study in detail the Rubens ceiling paintings, their fabrication technique and current condition.

The Banqueting House is the last surviving building of Whitehall Palace which was destroyed by fire in 1698 (Figure 1). Set within a decorative coffered ceiling designed by the building’s architect, Inigo Jones are nine paintings by Rubens, the artist’s largest and most accomplished works to remain in the context for which they were designed. The paintings were commissioned in about 1629 by Charles I as a testament to the glory of the Stuart monarchy through the depiction of his father James I’s life and achievements.

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The Main Hall at Banqueting House

These internationally significant paintings are an integral component of the architecture of the hall. Originally the Banqueting House Rubens ceiling paintings were oil-on-canvas stretched on strainers, but since 1907, they were attached to plywood boards. During their long history the paintings have been restored nine times—including in 1940 when they were cut up to evacuate the gigantic panels from the building.

High-resolution multi-spectral imaging

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Figure 2: Details of the multispectral gigapixel images of The Apotheosis of King James I panel (a. visible light, b. infrared reflected, c. ultraviolet-induced luminescence)

The first phase of our project involved capturing the condition of the paintings in high resolution images (Figure 2). The scale of the paintings, covering a total surface of 243 m2, and their position 17 m from the ground, made this task particularly challenging; however, recent advancements in digital photography helped us to overcome these difficulties.  Collaboration with imaging specialists developed the application of GigaPan technology to document all nine paintings from the ground in visible light and infrared light as panoramic ‘Gigapixel’ images. Ultraviolet-induced luminescence images were taken at close-range from a scaffold, by illuminating small sections of the painting and later stitching the images together to full-painting size. Superimposing the visible, infrared and ultraviolet images allows analysis and detailed classification of the current condition of the paintings as a standing record. This will underpin further investigations and inform the programme of conservation of these important paintings.

We would like to thank the following external collaborators for their expert insights and contributions to the successful progress of this cross disciplinary project: UV/IR imaging Dr Giovanni Verri (Courtauld Institute of Art) and Steven Paine (Paine & Stewart), 3D laser scanning, visible ‘Giga’ imaging John Hallett Jones (Glanville Consultants).

Assessing the light fastness of 16th century Indian paintings (Michela Rampa)

Next in our British Science Week 2018 series, Michela Rampa talks about her student placement at The British Museum, analysing colours in 16th century Indian paintings and assessing light sensitivity. Find out more at The British Museum’s British Science Week event on Saturday 17 March.

Hello, my name is Michela Rampa. I am a student from the University of Rome, La Sapienza, in Italy where I am studying to become a museum scientist. I am currently doing a student placement at The British Museum for my final dissertation. What a fantastic opportunity!

At The British Museum I am based in the Scientific Research Department but also regularly meet with conservators. I am learning how to assess whether museum objects might fade when exposed to light using “microfadeometry”. Microfadeometry is a technique that involves exposing a very small area on an object to an intense light for a short amount of time and recording the colour change on this small area. By comparing the colour change with references, it is possible estimate whether the object is sensitive to light or not.

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Examination of a 16th century Indian painting

Why is it so important to assess the lightfastness of museum objects? Many museum objects are light sensitive, for instance: watercolours, prints or textiles. We cannot stop fading from occurring when these objects are displayed, but we can ensure that light-sensitive objects fade so slowly that they will be seen by countless generations of visitors to the Museum in the future. Knowing if an object is likely to fade when exposed to light helps curators to decide how long  it can be displayed and under which conditions. For example, microfading tests carried out on Hokusai’s iconic prints ‘The Great Wave’ and ‘Red Fuji’ last year showed that these should be displayed using dim light for a short amount of time (read about it here).

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Experimental Technical Imaging laboratory in The British Museum

I am currently investigating the lightfastness of some Indian paintings, which will go on display in the new Albukhary Foundation Galleries of the Islamic World at the end of this year. One of them is a very colourful Hamzanama painting made in 1500. (Hamzanama is a series of manuscripts, most of them illustrated, that narrate the legendary deeds of Amir Hamza, the uncle of prophet Muhammad). It is very valuable and I have identified at least 13 different colours on it! I expected that most colours on this painting were produced using mineral pigments and therefore would not fade. However, I am discovering that, on the contrary, several colours, such as green, are light sensitive! I am hoping to perform more analysis to find out why these colours are affected by light. Work in progress!

In the meantime, if you want to know more about the work scientists do at the British Museum, please come and find me and the rest of the Scientific Research team at our annual event ZOOM IN: a closer look at science on Saturday 17 March 2018, 10.00 – 16.00, in the Great Court at The British Museum. Learn about all of the different techniques that are used to analyse the Museum’s collections, handle different kinds of raw materials and see the latest behind-the-scenes technology in action. This is a FREE event too!

Michela can be contacted by email and on LinkedIn. You can find out more about the upcoming Albukhary Foundation Galleries of the Islamic World on The British Museum website.