Tag Archives: Poedua

The Conservation of Poedua – Part 15

One of the most rewarding stages of the treatment is the varnishing of the painting.  The new varnish layer returns the colours of the painting to the saturation and depth which were intended by the artist and it is when we feel like we are on the home stretch of the treatment!

We use a synthetic resin that was specially created for the conservation profession, which has very similar optical qualities to the natural resins that John Webber would have originally used.  It has favourable ageing characteristics, yellowing much less than the natural resins and remaining easily reversible with age.

The first layer of varnish was brushed and as can be seen in the photograph below, the change was dramatic.

 

The early stages of the brush varnishing of the painting. Photograph taken by Katherine Campbell, © Te Papa.

Once the varnish has dried and hardened the next stage of the treatment can begin.  Retouching, also known as inpainting, is carried out in areas of loss and abrasion, with the aim of reintegrating these areas so as not to draw the eye of the viewer.  We want you to see the beautiful painting, without the distraction of areas of deterioration.  We take care not to cover areas of original paint, our aim is not to return the appearance of the panting to its original state or make it look-like-new, the natural signs of age are retained and returning the appearance to the artist’s original intention is our aim.

Retouching along the bottom edge of the painting (with my feet up!). Photograph taken by Matthew O'Reilly, © Te Papa.

Once the retouching was complete a final spray varnish layer was applied to ensure an even level of gloss and saturation across the surface.

The painting was returned to its frame which has also undergone restoration that Matthew will be blogging about soon.

After just over a 12 months work, the treatment of Poedua is finally finished.  The painting will be put on display in Toi Te Papa on level 5 this week and we hope you get a chance to come and see it soon.

 

2010-0029-1; Poedua (Poetua), daughter of Oreo, chief of Ulaietea, one of the Society Isles; 1785; Webber, John. After treatment. Photograph taken by Kate Whitley, © Te Papa.

Katherine and I have enjoyed keeping you up-to-date with the treatment of this painting and hope that you have enjoyed it too!  We will continue to blog when exciting things come through the paintings conservation lab that are worthy of sharing with you!

The Conservation of Poedua – Part 14

 

We have had a very busy start to 2012, we have been working to have Poedua ready for display in March and preparing a number of paintings for the upcoming touring exhibition Angels and Aristocrats.

After the painting was re-stretched following the structural treatment, the old restorations including overpaint and old fills were removed.  The old fills and retouching were poorly matched to the original paint layer, in colour and texture, and in areas were broader than the damages, extending over areas of original paint.

A detail photograph of the old restorations over an old damage at the proper right inside elbow. Photograph taken by Melanie Carlisle, © Te Papa.

 

After the knowledge gained during the varnish removal and a number of further tests we determined that the only safe method for removing the old restorations was mechanically.  This involves very carefully scratching and chipping the additions away from the original layers.  This is done with small scalpels and dental tools under the stereo microscope.  It is very fine work and requires and strong and steady hand!

A detail of the same area as above after the old overpaint and fill material had been removed. The damage and loss to the original paint layer is revealed. Photograph taken by Melanie Carlisle, © Te Papa.

 

As you can imagine this is quite a time consuming process – each movement removing a barely perceptible amount, a square centimetre can take an hour or more.

 

Once all the old retouchings have been removed we can see the painting in its barest state – all that is left is the artists work and with the damages and deterioration exposed.  We record this with photographs before the next stage of restoration begins which involves adding to the painting to ensure the work reads according to the artist’s intent.

Overall image showing the complete clean - all surface dirt, varnish and old restorations have been removed. The damages and deterioration in the paint layer are exposed. Photograph taken by Melanie Carlisle, © Te Papa.

 

The first stage of restoration is the filling of the losses in the paint layer.  Many were revealed after the removal of the old restorations and the tiny pin hole loses caused by water damage in the lower centre of the painting were also filled.  We use commercial chalk based filler which has been tested and proven to have favourable ageing qualities, remaining reversible with time.

Overall image after the new fills have been added to the losses in the paint layer. Photograph taken by Melanie Carlisle, © Te Papa.

 

It is very important to emulate the paint layer texture in the fills and in the cause of this painting the texture is predominately the twill canvas texture showing through the very thin paint layer.  Under raking light we use small spatulas, scalpels and dental tools to create the required texture.

Detail of the same area as above after the new fill material has been added. Photograph taken by Melanie Carlisle, © Te Papa.

 

The painting is now ready for the first layer of varnish!

Come and hear about the conservation of the painting when Katherine and I present our work on Monday 5 March at Te Papa.  Find out more here.

The Conservation of Poedua – Part 13

The varnish removal is finally complete!  The detail of the brushwork in the Poedua’s face and hair have been revealed and we are one step closer to getting this painting ready for display.

The canvas face down on the table with the stretcher removed (which can be seen on another table in the top right). The leather weights hold the canvas in position while it is loose. Photograph taken by Melanie Carlisle, 2011. © Te Papa.

The canvas face down on the table with the stretcher removed (which can be seen on another table in the top right). The leather weights hold the canvas in position while it is loose. Photograph taken by Melanie Carlisle, 2011. © Te Papa.

During the varnish removal we discovered a damage on the stretcher which meant that we needed to take the canvas off the stretcher for structural repairs.  We were hoping to avoid this step to maintain the historical integrity of the original attachment of the canvas to the stretcher, but in the end the care of the painting would be compromised if we did not.

We lay the painting face down on a clean table covered with Tyvek and carefully removed the original tacks from the tacking edges and lifted the stretcher away from the canvas.  There was an enormous amount of dust caked onto the canvas and the stretcher member at all sides, particularly at the bottom edge.  This gave us opportunity to clean the canvas and the stretcher in these areas.

At the bottom edge of the canvas lots of caked-on dirt was found which was caught behind the stretcher member. Photograph taken by Melanie Carlisle, 2011. © Te Papa.

Even more dirt in the bottom corner, plus some pieces of straw (most of the straw was removed when the painting was still in London - see previous post). Photograph taken by Melanie Carlisle, 2011. © Te Papa.

Even more dirt in the bottom corner, plus some pieces of straw (most of the straw was removed when the painting was still in London - see previous post). Photograph taken by Melanie Carlisle, 2011. © Te Papa.

Next we attached a strip lining to the canvas for two reasons, to add structural support to the brittle and fragile original tacking edges, especially in the corners and also to allow us to have something to hold onto when restretching the canvas onto the stretcher.

The join in the stretcher and the offending split in the wood. Photograph taken by Melanie Carlisle, 2011. © Te Papa.

In the above photograph the damage to the stretcher can be seen.  This part of the join was just too thin and has split apart.  The split area was pressing against the back of the canvas which was why it was essential to remove the canvas from the stretcher for this repair.  We discussed options for the structural repair of the stretcher with our object support team and decided on removing part of the stretcher and replacing it with a wooden insert.

A small section of the stretcher surrounding the damage was removed using chisels. Photograph taken by James Kirk, 2011. © Te Papa.

The repaired join after the wooden insert has been attached. Photograph by Melanie Carlisle, 2011. © Te Papa.

The repaired join after the wooden insert has been attached. Photograph by Melanie Carlisle, 2011. © Te Papa.

This interventive treatment was seen as the best way of maintaining the historical integrity of the original stretcher.  In the past the original stretcher may not have been giving the same importance and would have been replaced with a new and improved stretcher but modern conservation practices dictate a much different approach.

The stretcher was repaired, cleaned of the dust and dirt and reassembled.  We restretched the canvas, attaching the strip lining at the reverse of the stretcher using stainless steel staples.  The original tacks were cleaned or loose dust, dirt and corrosion in an ultra-sonic bath and then replaced in their original holes in the canvas and the stretcher.

Katherine and I restretching the canvas and attaching the strip lining canvas at the back with staples. Photograph taken by Drew Ward, 2011. © Te Papa.

Katherine and I restretching the canvas and attaching the strip lining canvas at the back with staples. Photograph taken by Drew Ward, 2011. © Te Papa.

The tension of the canvas has been improved and the fragile tacking edges are now supported by the strip lining.  Next is the removal of the old overpaint and fills which we will discuss in our next post in the early new year.

The Conservation of Poedua – Part 12

Hello. Matthew O’Reilly, Framer of Paintings, returning to the subject of Poedua, and particularly, her lovely frame.

This is my second post about the conservation of the frame. The first one was in June, and it dealt with understanding the frame and its history well enough, and identifying the questions to be answered, before and so that, appropriate decisions could be made about the course of treatment of the dirty and damaged, but beautiful and historic frame. I have been kept from beginning the treatment until about a month ago, and have been working on it intermittently since.

In my first post I noted a previous restoration on the outer sides of the frame, a regilding over a new layer of gesso and red bole. (Gesso: white chalk and rabbit skin glue; and bole: clay and rabbit skin glue — materials traditionally part of gilding systems on wooden furniture, frames, etc.)  I had noted from the beginning, the use of  “bronze” (which is actually brass!) paint here and there to cover damages to the gilding and gesso underneath, and noted further similar damages to the surface made since the use of the paint. I had noticed holes in the surface and in the wood on the back showing European woodworm attack (rather like borer-holes only a little larger in size). 

Since turning my attention back to the frame I have discovered that the front of the frame has largely all been regilded whether at the same time as the outer side regilding or on a separate occasion. One difference is that there is no additional gesso and bole layer on the carved details on the front, but signs of some partial regessoing on the flats. The best thing about not being regessoed is the retention of the detail in the carving, and most of the subtlety of form in the profile.

As has been shown quite frequently in examining older frames, the historical restoration involving regilding appears to have been a mixture of expediency (time spent = money spent) and the attention to respectful appearance (appropriate materials and technique). The front of the frame seems to have been regilded using the same methods as the original, as opposed to the far less subtle treatment of the forms on the outer facing surfaces. Later use of bronze paint to cover small damages is an example of still greater expediency with a poorer outcome: the paint also covers adjacent surfaces that were in otherwise reasonable condition, and the paint has gradually changed in colour to the very dull green that you can see here and there in the images below.

In the interim, the decision was made to return the frame as best we could to a level of brightness (the virtue of its covering of gold leaf) commensurate with the return of the painting from its darkened state, by cleaning the surface appropriately, so that the painting and frame would present in a unified manner once back on exhibition.

Given that the painting itself is becoming lighter as Katherine and Melanie find their way down to the original colour and tonality of the paint, as they remove the historical layers of dirt to reveal the painting closer to the intended appearance of John Webber, then it follows that the frame should also rediscover more of its earlier colour and tone. A frame importantly serves the aesthetic requirements of the painting it encloses as well as connecting it to the aesthetic requirements of the milieu in which it once resided. Indeed it is probably now the only evidence of that milieu.

As you see from the earliest images of the frame the dirt was unevenly distributed across the frame. Bearing in mind that the frame is fairly big at about 1650 mm high, there was a graduated appearance from least dirty on the upper and high on the right members (i.e. brightest), to most on the lower member (i.e. least visible gilding), and showing some difference in the amount of dirt also from right to left. I decided not to attempt a wholesale removal of the later regilding, since reasonably large areas of it, especially in the upper parts were in good condition, but rather to retain what was still good in it, and then to restore where necessary to a point of reintegration.

It was first necessary to define the different methods of gilding utilised on the frame, in order to decide which cleaning material to use. The unadorned surfaces are all gilded using water gilding while the carved work is mostly gilded with oil size; the later regilding is consistent with the original in the techniques employed. I decided to clean the carved, oil-gilt parts first and it is this I am working on at present.

So I have begun cleaning the grimy and often hardened sooty materials from the carved parts, discovering that the worst areas, mostly towards the lower section, have some damages that reach right through the various layers, with multiple interactions between the layers and the different materials of the original and later restoration additions and dirty surface depositions as far as the chalk or gesso, making an uncomplicated removal of the dirt impossible in many places.

Lower member centre-right during swab cleaning. Photograph by Matthew O'Reilly. © Te Papa.

I am using on the oil-gilt carved parts an acqueous cleaning agent applied with a cottonwool swab. This has shown to be effective in most parts but there have remained some more intractable areas of hardened deposits including flyspots, and places where the interaction through the surface layers mentioned above has left those layers physically and visually compromised. These parts have required some mechanical picking with a metal tool to smooth the degraded materials and remove the acretions sufficiently, so that when the reintegration is complete, the frame will once again present the painting acceptably.

Left member centre, showing a typical area of surface damage. Photograph by Matthew O'Reilly. © Te Papa.

Still to come: included in the visual reintegration of the frame surface will be the consolidation of various areas above the wooden carcase, particularly the gesso substrate where in some places the glue binder has broken down and is no longer holding well. This problem has apparently been suffered by the frame for a long period of time judging from the numerous small losses of surface material, which long ago gave rise to the use of the bronze paint, now green. And one of the corners will need to be disassembled and realigned, requiring in the process at least one other corner to come apart, before being put together again. But more of this aspect of the treatment in a later post.

The Conservation of Poedua – Part 11

The varnish removal of Poedua is progressing slowly and painstakingly and we are now almost halfway through this important part of the treatment.  As we have mentioned before, removal of discoloured varnish can have a dramatic effect on the overall balance, colour and depth of a painting.  Because discoloured varnishes like Poedua’s are usually a yellow-brown colour, they tend to reinforce warm tones but counteract the cooler colours such as some greens, whites and cooler blues.

Flowers before cleaning

This image shows Poedua's face and the flowers pre treatment - before surface cleaning and varnish removal. Photograph taken by Michael Hall, 2011 © Te Papa

Every week we are recovering more of the artist’s original paint from beneath the discoloured varnish and overpaints and we have made some nice discoveries.  Most recently, we have revealed the beautiful colours and brush-stroke detail of the flowers in Poedua’s hair. 

Poedua flower after cleaning

In this image after cleaning, you can now see much more detail in the brush-work of the artist and appreciate all the colours of his palette. Photograph by Katherine Campbell, 2011 © Te Papa

Before we cleaned them, the flowers were quite dark and a little cloudy, making them a bit difficult  to interpret.  Now that the surface dirt and varnish has been removed you can see the lovely detail of the brush-work and full range of colours employed by Webber.

Poedua's flower after cleaning

This image shows the difference in appearance after cleaning of Poedua's hair, face and the flower. Photograph by Katherine Campbell, 2011 © Te Papa

The Conservation of Poedua – Part 10

Hello everyone, we are back with our fortnightly updates on the treatment of John Webber’s Poedua.

We are progressing slowing with the cleaning of the painting.  At this stage, the cleaning involves the varnish removal and the removal of overpaints (later additions by a previous restorer).

The painting on the easel in the Paintings Conservation lab. You can see some areas where the varnish has been removed; the sky to the right of Poedua's arm and square patches in the tapa cloth. Photograph taken by Melanie Carlisle, 2011. © Te Papa

Today’s blog post will focus on one stage of the cleaning – the removal of the paper label which was attached to the face of the painting down in the bottom right corner.  This label may have been attached for a sale or an exhibition that the painting was once in.  The paper label had been completely saturated with varnish, which made it resistant to the aqueous solutions that we would normally use on paper.  Using the same solvent solution we have been utilising for the varnish removal, we drew as much of the varnish out of the paper as possible and then applied a methyl cellulose gel to soften the paper label which allowed it to be removed.

During the removal process. This image shows the paper label coated with a layer of methyl cellulose. The Mylar on top ensures the methyl cellulose does not 'dry-up'. Photograph taken by Melanie Carlisle, 2011. © Te Papa

We discovered that there were actually two paper labels, as well as the remnants of another, one on top of the other, which we managed to separate during the removal process.  We took great care to remove the labels whilst keeping them as intact as possible.  The paper remnants were removed first which revealed the topmost label.

The topmost label once the paper remnants had been removed revealing 36. Photograph taken by Melanie Carlisle, 2011. © Te Papa

The topmost label suffered a few small tears during the removal while the lowest remains completely intact.  We cannot disregard this type of information which may assist in research into the provenance of the painting.  The numbers 8 and 36 may correspond with a lot number at a sale or a listing number in the catalogue for an exhibition.

Once the first label was removed, this label was revealed with the number 8. Photograph taken by Melanie Carlisle, 2011. © Te Papa

 

So no matter how small, information like this is very important and care must be taken to retain it.  It would have been easier to remove these labels in a method which destroyed the information, but if we are doing our job thoroughly it’s not about choosing the easiest methods or getting the fastest result!

The Conservation of Poedua – part 9

Hello Poedua followers!  Mel and I have taken a break from our treatment of Poedua for a while in order to focus on some other paintings conservation commitments.
 
In the past two months we have been kept busy working on a loan of 23 paintings for the exhibition Painting New Zealand which is currently on display at Tauranga Art Gallery. 
 

We have prepared a number of paintings that have been on display in the Te Papa touring exhibition E Tu Ake, which will soon be making its international debut at the Quai Branly in Paris.

Lastly, but by no means least, we have also been very busy working on the upcoming Oceania exhibition which will be opening soon at Te Papa and City Gallery Wellington.  The Tony Fomison painting below is one of the many art works that will be on display in the Oceania exhibition which is on during the Rugby World Cup.

Te Puhi o te tai Haruru, 1984-85, Fomison, Tony (1939–1990), Auckland. Purchased 2003. Te Papa

Te Puhi o te tai Haruru, 1984-85, Fomison, Tony (1939–1990), Auckland. Purchased 2003. Te Papa

If you are missing your fortnightly Poedua updates, here are a couple of other conservation blogs that you may find of interest from some overseas colleagues. The first is written by Hannah Tempest who interned with us last year and is currently undertaking an internship at the National Gallery of Denmark in Copenhagen. The second is written by conservators at the National Gallery of Victoria in Melbourne and follows the conservation of a Nicolas Poussin painting.

The Conservation of Poedua – Part 8

If you have been following Mel and Katherine’s Poedua treatment blogs you may be surprised to read another’s voice on this one – a voice from the edge as it were. I’m Matthew O’Reilly, Framer of Paintings here at Te Papa. My previous blogs were quite some time ago now. Katherine and Mel have needed to take a short break from Poedua, so in order to keep the rhythm going I shall begin my contribution to the Poedua story (always intended) now. My first post on this subject presents a provisional view on the origins of the beautiful frame.

As will be plain from the accompanying photos a lot of remedial effort will be required for the frame to present the painting as befits its role; the conservation will be the subject of later posts. This post summarises the preliminary process.

From the time I first sighted Poedua in her frame the ensemble that they made excited me instinctively and aesthetically. The frame, like the painting, gives one a strong whiff of the Neo-classical period, with its strict rhythms of transverse elements of motif bounded with clarity by bright stepped bands, and gives its matching to the painting a special sense of period authenticity and authority; the aesthetics of its form and scale a sense of rightness as a means of carrying the painting and its subject forward through time. It helps to place her in history as well as any but the most clearly documented original framing: together they admirably represent the junction of the Enlightenment impulse that took Cook to the Pacific, the contemporary currency of Neo-classical style, and the incipient Romanticism symbolised by Webber’s subject.

Image of Poedua in its frame immediately after it arrived at Te Papa. Photograph taken by Michael Hall. © Te Papa.

Image of Poedua in its frame immediately after it arrived at Te Papa. Photograph taken by Michael Hall. © Te Papa.

The frame and its relationship to the painting. A hunt for clues.

In assessing treatment options for picture frames it is important that all possible evidence is gathered about their provenance as distinct from that about the paintings they contain, so that the best quality treatment decisions can be made — especially concerning appearance. Whether they mean to or not, picture frames play a critical role in representing context, which consequently makes them very important in the isolating milieu of the museum. It is very important that they serve their paintings well in this respect.

I am due to start on this frame’s treatment soon. As that proceeds more facts that go to a greater clarity about the frame’s relationship to the painting may or may not emerge, and curatorial research into the historical life of the painting may yet throw some light on just when it arrived on the painting.

To sum up the evidence so far gleaned from observation of the frame, research of available literature, and some opinions from colleagues across the globe, it is possible for me to say for sure only that the frame fits within the general period of the painting and has an aesthetic correspondence that resonates sympathetically with it, connecting it well to the period when the painting was made.

Yet Poedua is not the first painting this frame has protected and presented. It may have been put on Poedua when the painting was made, and could be ten or fifteen years older than the painting; or it may have arrived on it after its arrival in France. So far, I have been unable to determine clearly whether the frame is English or French, but it is likely to be one of these. And despite the sense of rightness, clear evidence about the conjunction of the frame and painting is not yet there.

The painting is known to have spent much of its life in France. Perhaps too much can be made of the frame’s French stylistic inheritance as evidence, even as it obliquely interprets the painting’s historical journey so well. I can’t claim to be able to pinpoint from the evidence of the frame itself where and when it was made but think there is enough evidence to support its continued pairing with the painting.

This is not to say that this is necessarily this painting’s first and only framing, but is to say that it could be, and we at Te Papa will treat it as if it were so. There follows a summary of the clues that the examination of frame has yielded so far to support the frame’s authenticity to the general period from which the painting comes, even if it was not the painting’s first frame. I do hope that time and further research will tell a more detailed story.

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A reminder here: the painting was made in London in 1785 or very close to it.

1. Style. The profile consists of two main components rising from the picture surface, the inner and larger in scale being a scotia or cove (C-curve) carved in relief with transverse motifs; and the outer and upper one, smaller in scale and ogee (S-curve) in form embellished with transverse carving in relief. This doubling effect of two layers of transverse motif separated by plain bands of gilding is the most striking element of this design of frame which would tend to limit the probability of its production to perhaps 1770 at earliest and 1810 at latest. The origin of the style lies in France, but its uptake into England was very quick and some more teasing out of the motifs themselves and how the carver has treated them is required to come to a strong opinion as to which country it comes from.

2. Materials and techniques. The frame is hand-carved and gilded onto red clay and gesso. Hand-carving means the relief ornamentation is cut out of the wood of the carcase of the frame members, and is not an enrichment made from plaster work and applied to the carcase. In statistical terms this fact increases the likelihood of an earlier rather than later dating, and is more likely to put it in the eighteenth century than the nineteenth. The thinness of the gesso layer of the original surfaces and lack of surface texturing may suggest an English origin. Against this however the use of some hard wood in the carcase seems to dispute this conclusion, and lean it towards France.

Upper left corner detail at the back showing cut-down mitre with remnant of original key plus later key across mitre. Photograph taken by Matthew O'Reilly. © Te Papa.

Upper left corner detail at the back showing cut-down mitre with remnant of original key plus later key across mitre; compare with upper right corner image. Photograph taken by Matthew O'Reilly. © Te Papa.

3. Historical alterations. There have been two clear interventions on this frame since it was first made. One of them in particular has some direct relevance to our search for understanding. That is, the frame has been cut down from its original dimensions. Occurrences such as this are remarkably common and come as no surprise. The painting itself does not appear to have been reduced in size, and is not one of a number of standard sizes that were common in Britain in the eighteenth and nineteenth centuries. The frame was cut down to fit a non-standard size painting, and so we can surmise that it was cut down for our painting. By examining the evidence of the carved corner motif on the front and the cross keys on the back used to strengthen the mitre joints, we know how much was cut from the two mitres and that the original frame aperture corresponded neither to the standard canvas sizes common in England or those (different ones) common in France. The other intervention to the appearance of the frame, involving a regilding of the outer sides, I shall return to in a later post as it does not bear on this discussion of authenticity and origin.

In our part of the world the sense of rightness of matching of painting and frame is all too rare and I delight in this occurrence of it.

The Conservation of Poedua – Part 7

In the paintings conservation lab, we have been working away steadily on the varnish removal of Poedua.  Every now-and-then we come across a painting where this stage of the treatment is relatively easy, where a simple organic solvent solution is effective in removing the varnish without any effect to any part of the underlying paint layer.  More often than not the treatment of varnish removal is more complicated and Poedua falls into this category!

There are many factors which make the treatment of varnish removal different for every painting that comes into the lab.  The materials and techniques of the artist are a contributing factor and with this painting the extremely thin paint layer and the use of glazes have resulted in the difficulties in the treatment.

The pale spots on the arm of Poedua are areas where the varnish has been removed. The exposed paint layer appears matte and dry and will be saturated again once the painting is revarnished. Photograph taken by Melanie Carlisle, 2011. © Te Papa.

More varnish removal test areas. The white hazy areas on some spots are caused by varnish residues remaining on the surface. This occurs when the solution does not work effectively at removing the entire varnish layer. Photograph taken by Melanie Carlisle, 2011. © Te Papa.

 Our initial testing identified some issues and we have had to stop and reassess our options and consider more complex cleaning strategies.  This is not unusual!  Varnish removals are the most complex treatments that paintings conservators perform and this is a part of our working process.  We begin with simple solutions and build up to something more complex when necessary.

Melanie cleaning a small test area in the drapery. Photograph taken by Katherine Campbell, 2011. © Te Papa

The same area after the varnish has been removed. Photograph taken by Katherine Campbell, 2011. © Te Papa

We have now formulated a method for removing the varnish layer from Poedua.  Our progress will be constantly monitored throughout the treatment.  It is a slow process, but the result will be worth all the time and effort.

The conservation of Poedua: part 6

Now that the painting has had its layer of surface dirt removed, the next step in the treatment is the removal of the varnish layer.  A lot of the principles that we talked about with surface cleaning, also apply to the removal of varnish layers.  Therefore, prior to beginning it’s important to establish as closely as possible what the varnish or coating is, consider whether it is appropriate to remove it and work out a strategy for removing it safely.
 

In the case of Poedua, we want to remove the varnish layer because it is very discoloured and has been applied extremely unevenly, which has become more apparent as the discolouration has progressed.  Similar to the effects of surface dirt, the discoloured varnish present has diminished the tonal ranges of the painting.  

 
Uneven varnish under UV

Under UV the uneven application of the varnish becomes really obvious. The bright green fluorescence indicates a natural resin varnish, 2011. Photograph by Mel Carlisle © Te Papa.

The first step is to characterise the varnish and work out how many layers are present.  There are several techniques available to us including, exposing the painting to ultraviolet light and taking cross-sections of the paint and varnish layers.  Looking at the painting under UV lamps causes specific auto-fluorescence in different materials which helps us with identification.  The varnish layer on Poedua fluoresced a bright green colour, indicating a natural resin such as dammar or mastic.  This wasn’t surprising to us since both are common varnishes that we might expect to find on a work such as this. 

Cross-section analysis involves the sampling of a microscopic piece of the painting, usually taken from an area of existing damage.  This sample is set in a polyester resin and ground down with fine sand paper.  The cross-section is then examined using a compound microscope where we can see the building up of paint layers by the artist, surface coatings and later additions.  From the cross-section we took from Poedua we can see that there is only one varnish layer apparent.

Viewing the cross-section under magnification

Once the cross-section has been prepared, we look at it under magnification and also UV to see the build-up of layers used by the artist, 2011. Photograph by Katherine Campbell © Te Papa.

 

Cross-section under UV and magnification

This a cross-section taken from a Don Driver painting in Te Papa's collection. 1980-0013-1; Zither; Don Driver. Under magnification and UV it's possible to see several layers of paint and 2 layers that fluoresce with the appearance of varnish. The cross-section was photographed by Sarah Hillary at the Auckland Art Gallery, 2010 © Te Papa.

Varnish layers become increasingly difficult to remove the older they are.  This is due to alterations in their chemical structure that occur over time.  The solvents that conservators use to remove varnishes are carefully tested in a similar manner to the surface cleaning testing.  We use a variety of solvent mixtures and different preparations and combinations including enzymes, soaps and gels.  Their effectiveness builds further on our knowledge about the varnish layer we are dealing with.  Solvents work by penetrating the varnish layer and swelling the film, bringing the resin into solution and allowing it to be removed from the surface.  After initial testing, we select the most appropriate solvent or solvent mixture and test this in the various areas of the composition.   Constant care and attention is crucial during this process because the varnish layer is usually the last layer before the paint film is encountered.

Testing the varnish solubility

Initial testing is done under magnification so we can closely monitor the results. As with the procedure for surface cleaning swabs are kept along with notes of the results for comparison, 2011. Photograph by Mel Carlisle © Te Papa.

 

Varnish removal tests

Once the pale paints have been tested we move onto all the major areas of colour. The two circular areas that appear dry and matt are the patches where the varnish has been removed and the paint layer is exposed. At the end of the treatment a new varnish layer will be applied which will resaturate and intensify the paint surface again, 2011. Photograph by Katherine Campbell © Te Papa.

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