Tag Archives: Paintings Conservation

The Conservation of Poedua: Part 4

27 April 2011 – 3.23pm

Now that we have cleaned the back of the canvas we can look at surface cleaning the front of the painting.  This is a separate procedure from the removal of varnish and overpaints and is completed first because surface dirt is the first layer encountered.  The reason we remove the dirt layer on paintings is because it considerably alters the colour and tone of original paint, can obscure image detail and significantly alter the surface gloss, clarity and hue of surface coatings.

Surface Cleaning

Detail; 1992-0035-1883; Lake Manapouri; Baker, William George; During treatment. The cleaned rectangular area at the left shows you what a difference surface cleaning makes to the appearance of a painting, 2006. Photograph by Katherine Campbell © Te Papa

Surface dirt is a mixture of all sorts of quite unpleasant things including flakes of skin and hair, smoke from household fires and tar from cigarettes, food and drink deposits, moulds and fungi, insect debris and general atmospheric pollutants!  To remove the surface dirt, it is necessary to overcome the bonds that are holding the dirt to the painting without disrupting the underlying paint layer.  To find the safest cleaning formulation we carry out a process of testing different mixtures through careful application and monitoring of the results.
Testing notes

As we go through the testing process to find the best cleaning formulation, we keep a detailed written record of what we used and how well it worked, 2011. Photograph by Katherine Campbell. © Te Papa

When we carry out our testing, we apply the cleaning solutions with small cotton swabs in a rolling motion over the paint surface.  We test inconspicuous areas first, starting with light colours and then progress to all the main paint colours.  We keep and label the test swabs for comparison.  We often have to reassess our cleaning strategy because the solubility of dirt and paint can change across the surface of the painting requiring the use of different materials and concentrations of solutions. The most common surface cleaning agents are aqueous in nature – meaning they are water-based.  We can modify and control the properties of the water by adding pH buffers and ionic buffers and by adding chelating agents, surfactants, enzymes and gelling agents.

Mel mixing

Mel carefully makes up a testing solution to trial on the painting, 2011. Photograph by Katherine Campbell. © Te Papa

Last year I was able to attend a course in Melbourne about the cleaning of paintings using the Modular Cleaning Program.  This is a database system and an approach for cleaning paintings that has been developed to help conservators use established theory and materials in a way which makes the complicated chemistry of cleaning more accessible.  Basically, the computer program is better at working with piles of numbers than us!  It saves us time by working out the complicated stuff, like ionic equilibria, which requires pages of calculations and is really boring and not to mention, tough!

MCP

With the help of the modular cleaning program, we are able to make up and test a wider range of formulations than we would ordinarily have time to do, 2011. Photograph by Mel Carlisle. © Te Papa

Through our testing and the help of the Modular Cleaning Program, we arrived at a solution containing a mixture of enzymes which we will use to safely and effectively surface clean Poedua.  The next blog post will talk about the surface cleaning process now that we have found our cleaning agent and will include some nice images of the cleaning in progress. 

spliced image

Once a suitable cleaning formulation has been found, all the paint colours utilised in the composition are tested to make sure of its suitability. The small circular areas are the cleaned test patches, 2011. Photograph by Katherine Campbell © Te Papa

By Katherine Campbell | Posted in Art, Conservation, Pacific | Also tagged , | Comments (5)

The Conservation of Poedua – Part 3

13 April 2011 – 2.53pm

After completing our technical examination of the painting, taking lots of pre-treatment photographs and writing the condition report, we write a treatment proposal for the painting.  We consider the current condition of the painting and what we would like to achieve with different treatments.  Our proposal is discussed with the curator and together we outline the aims and objectives of the treatment.  No cleaning of a painting is without risk so all options need to be discussed.

The treatment schedule for Poedua begins with surface cleaning the reverse of the painting.  Methods of surface cleaning fall into one of two categories; Dry, where brushes, tweezers, erasers and/or sponges are used to lift and remove surface dirt from the surface; or Wet, where aqueous solutions, solvents or gels are used to lift and remove the surface dirt.  Generally for paintings on canvas we begin with cleaning the reverse of the painting using dry surface cleaning methods.

For Poedua the cleaning of the reverse of the canvas occurred in a number of stages.  It began all the way back in November when the painting was still in London.  To prepare the painting for travel, dust and debris were removed from the area between the canvas and the bottom stretcher member.  This was removed because the pieces could have moved around during transit and caused damage.

 

A pile of dust removed in London before the transit of the painting. The debris included straw fragments and an old nail. Photograph by Melanie Carlisle, 2010. © Te Papa

Forward a few months and the painting is in the conservation lab.  We carefully lay the painting face down onto a clean table and use a brush and an indirect vacuum (holding a vacuum on low power above the canvas rather than touching the canvas with the vacuum) to remove the loose dust and dirt particles.  

Dusting the reverse of the canvas with a brush and indirect vacuum. Photograph taken by Katherine Campbell, 2011. © Te Papa

This was only partly successful so we cleaned further using small pieces of dry cleaning sponge to lift dirt that was caught in the interstices of the canvas weave.

Katherine cleans the reverse of the canvas with a dry cleaning sponge. Photograph by Melanie Carlisle, 2011. © Te Papa

Finally we removed more dust and debris which was caught between the canvas and the bottom stretcher member.  It was impossible to complete this part of the treatment in London because of the restrictions of materials, time and place.  We held the painting up at the bottom edge and left the top edge resting on the table to allow the dust and debris to fall away from the painting.  We used a variety of tools to carefully remove as much as possible from this area.   

As I hold the painting, Katherine uses a palette knife to gently dislodge dust and debris caught between the stretcher member and the canvas. A pile of dust can be seen on the table top. Photograph by Matthew O'Reilly, 2011. © Te Papa

Our treatment of surface cleaning the reverse of the canvas has resulted in the inscription being clearer and easier to read.

In the centre of this photo the canvas has a grey appearance where it is yet to be cleaned. The P of Poedua has been cleaned and is clearer and easier to read. Photograph by Katherine Campbell, 2011. © Te Papa

By Melanie Carlisle | Posted in Art, Conservation, Pacific | Also tagged , | Comments (1)

Conservation of Poedua, part 2

30 March 2011 – 11.13am

Poedua is an oil painting on stretched canvas, meaning the composition is painted on a fabric support which is stretched to keep it evenly tensioned, over an expandable wooden stretcher.  Canvas supports began to replace traditional wooden panel supports from about the 16th century and were the most commonly used type of support by the 18th century. 

The back of the canvas

In this photo you can see the back of the canvas support and the wooden stretcher frame which keeps the canvas taut, 2011. Photograph by Michael Hall. MA_I.227733 © Te Papa

The canvas used for this painting is probably linen (untested) and it has a twill weave, which creates a distinct texture which is visible through some areas of the paint layer.  Linen is a common support for paintings of this age, but other fabrics are also used as supports for paintings, including hemp and cotton.  The canvas is attached with small metal tacks around the sides of the stretcher bars.  We think there’s a good chance that this is probably the original attachment because there are no old holes in either the canvas or the stretcher, which can indicate that the canvas has been taken off in the past.

Here you can see a profile view of the painting showing a metal tack attaching the canvas to the stretcher, 2011. Photograph by Michael Hall. MA_I.227731 © Te Papa

The back of the canvas is no longer looking as it would have when Webber first painted it!  The canvas is made of a natural fibre which has darkened and discoloured because of the process of ageing and deterioration.  We have found the canvas to be in quite a good condition, given its age.  There are a few areas we will need to address in our treatment, including some small tears and embrittlement around the edges.  This has occurred because over time the fibres have become inelastic and snap rather than stretch.  There are some areas of damage which we can’t determine the extent of just yet because they have been covered with patches on the back.

Patch

Detail of one of the old patches on the back of the canvas. At this stage we are unsure what the patch is covering, 2011. Photograph by Michael Hall. MA_I.227733 © Te Papa

The back of the canvas is also dirty from being exposed to the world for the past 226 years!  There is a layer of dirt and some staining present, which are a combination of age-soiling and various deposits and residues.  We hope to be able to reduce some of this soiling with cleaning, but this action probably won’t dramatically change the way the canvas currently appears.  What we hope to achieve is a reduction of the dirt matter, which if left, can accelerate deterioration.

An interesting discovery for us is that Poedua has never been lined.  Lining is the attachment of a new support to the entire reverse of a painting on canvas.  Its aim is to give additional support and reinforcement to a weakened or damaged canvas.  It was a very common restoration procedure in the past and most paintings of this age have been lined at some point.  The fact that the canvas has remained unlined means that we can see the back of the original canvas and a lovely inscription, presumably by the artist himself. 

Poedua inscription

Detail of the handwritten inscription on the back of the canvas. The inscription includes information such as the subject's name, her father’s name and the location of their village. Some of the inscription is unclear and we are hopeful that cleaning will reveal it more, 2011. Photograph by Michael Hall. MA_I.227733 © Te Papa

 
 
By Katherine Campbell | Posted in Art, Conservation, Pacific | Also tagged , | Comments (2)

The conservation of Poedua – part 1

16 March 2011 – 1.16pm
Poedua (Poetua), daughter of Oreo, chief of Ulaietea, one of the Society Isles, 1785, Webber, John (1750–1793). Purchased 2010. Te Papa

Poedua (Poetua), daughter of Oreo, chief of Ulaietea, one of the Society Isles, 1785, Webber, John (1750–1793). Purchased 2010. Te Papa

Welcome to the first blog to keep you up-to-date with the conservation treatment of John Webber’s portrait of Poedua.  Katherine Campbell and I, the two paintings conservators here at Te Papa, will aim to post fortnightly on the progress of our work, offering you insight into what happens to a painting during a conservation treatment.

The painting arrived in the paintings conservation lab shortly after being taken down from display in Toi Te Papa.  Our first task was to remove the painting from the frame and to remove the temporary backing board which had been attached to the reverse of the painting for the transit from London to Wellington.  This is done in order to gain unimpeded access to the whole work, from the front and back of the canvas.

Katherine examining the painting with a hand-held microscope, 2011, Photograph by Melanie Carlisle. © Te Papa

One of the most important aspects of a conservator’s job is documentation; we need to clearly record the current state of the artwork or object.  For a painting, this documentation is generally broken down for each of the paintings ‘layers’.  We begin at the auxiliary support (in this case the wooden stretcher), the primary support (the twill canvas), the ground layer (or priming, preparatory layer), the paint layer and the surface coating.

This report includes a detailed description of the layers, covering visual appearance and the artist’s technique; we also consider what materials were available to the artist and often reference colourmen’s catalogues from the time and place the painting was executed.  We also document the current condition of each layer, with possible reasons behind that condition and any ongoing issues of deterioration.   

It is this documentation that we have been working on for the past few weeks which will help inform us about what treatments to undertake.  We use a variety of different technical examination techniques to aid us in finding out as much as possible about the painting. 

Some of these techniques include examining the painting with different forms of illumination; using normal lighting sources, we look at the painting in reflected, raking and transmitted light.  We use UV lamps in a dark room to investigate the surface coating and any later additions by a previous restorer.  We use infrared photography to see through the paint layer and identify (if they are present) preparatory drawings as well as artists changes (pentimenti), damages and associated restorations.  We examine the individual brushstrokes using a stereo-microscope and get to know all the fine details in the painting.  We use these photographic images to help illustrate and complement the written condition report.

Infrared photograph - detail, 2011, Photograph by Michael Hall. MA_I227737. © Te Papa. The small red circle at the bottom shows the changes the artist made to the scale of Poedua's little finger (pentimenti). The larger red oval shows an area where the paint layer has been damaged and covered with a previous restorers overpaint.

 

Ultra-violet photograph of Poedua, 2011, Photograph by Melanie Carlisle © Te Papa - This image shows the auto-fluorescence of the natural resin of the varnish when exposed to ultra-violet light. The brushstrokes from the varnish application can be seen. The variation in the auto-fluorescence indicates the uneveness of the varnish layer.

Once this stage of the documentation is complete, we write a treatment proposal to outline what we hope to achieve with our conservation treatment.  The technical examination continues throughout the conservation process, we continue to learn more about the painting and the artist as we spend more time with the painting.

By Melanie Carlisle | Posted in Art, Conservation, Pacific | Also tagged , | Comments (7)
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