'A Black Piece' revisited

This post was written by Emma Schmitt from the Textile Conservation MPhil at the University of Glasgow, who is the summer conservation intern on the Conserving 'Curiosities' project.

Barkcloth 1886.1.1256

'Upon arriving at the Pitt Rivers Museum I was shown the bark cloth object on which it was assumed I would spend most of my time.  The “black piece", as it was listed in Forsters Catalogue, is an interesting and singular object in many ways.  The cloth itself is constructed of three layers, two of plain white bark cloth and one of a decorated black cloth.  The decoration, similar to that seen on the headdress of the Pitt River's second Tahitian mourner’s costume, is itself, rare in form.

1886.1.1637 .9 Headdress, Tahitian mourner's costume

Detail of barkcloth on headdress

At first glace this object is a bit scary, as you can see there are many areas of loss, but on top of that the black cloth appears to be flaking apart in some areas and powdering in others.  The painted areas easily lift up from the surface of the black bark cloth taking both the paint as well as bark fiber with it.  Every time the piece moves other small fragments are lost.

Detail of 1886.1.1256 showing surface damage

The construction of the object has had an effect on some of the damage.  The layers of this cloth have been lightly pasted together.  The black bark cloth has been pasted down in a rather haphazard manner causing creases and folds to form.  These folds can be seen in the photo and, in some places, correspond to the areas where the piece has been damaged. 

Black dyed fibers overall are susceptible to damage for one main reason.  Black dyes tend to be very high in tannin and iron and thus very acidic.  In an acidic environment the fibers can break down at the molecular level eventually leading to visible damage, like we see on this object.  For the most part black dyes in the South Pacific were made using extracts of bark, high in tannin, followed by immersion in mud that would have been high in iron.  Earlier research on this cloth shows that the black portion of the cloth is high in iron, explaining why the barkcloth was breaking down. 

1886.1.1256 - detail of surface under microscope x24

On initial examination of the painted decoration it looked as if white paint had been applied to the black cloth. However, under magnification, the paint appears to have originally been black and, for an unknown reason, appears to have bloomed with a whitish powdery substance.  The question was raised as to whether or not the paint might be a Western paint, brought on Captain Cook’s earlier voyage.  Without chemical analysis of this paint this question is difficult to answer.  The fact that the paint may be black, instead of white, means that it could easily be a local resin.  This still leaves the possibility of it being a Western paint open to speculation. 

While the investigation into the piece leaves numerous questions unanswered it posed a number of conservation issues which led to some interesting experimentation. 

As mentioned, this bark cloth is in poor condition, however it is a rare piece and thus incredibly important to the Pitt Rivers collection.  When we started to discuss possible treatments consolidation of the surface was discussed, to prevent the continuing loss of the back fiber.  Consolidation is the process by which an adhesive is applied to a surface to bind a material together to prevent further loss.  In many cases this is something down to more rigid objects like flaking or powdery painted surfaces.  In dealing with bark cloth the flexibility of the cloth is important and maintaining that flexibility is key to the treatment. 

Research into different methods of consolidation led to the work of Rangi Te Kanawa, a Maori Conservator based at The Museum of New Zealand Te Papa Tongarewa.   Ms. Te Kanawa’s work focuses on the conservation of Mari Cloaks.  Her recent research has lead to the use of sodium alginate, a seaweed based gel, as a consolidate for black dyed New Zealand flax.  Her research showed that, not only did the sodium alginate bind the deteriorating fibers together, but it also had the added benefit of neutralizing some of the acids that are the result of the mud-based dye process. 

Sodium alginate has not been applied to bark cloth by Ms. Te Kanawa so it was unknown how it would affect a very different material.  We set up an experiment to see whether or not the treatment would have a beneficial effect.  Solutions of sodium alginate were made up in various concentrations.  Using fragments of bark cloth from a store of unaccessioned samples we applied the solutions to a dry bark cloth fragment with a brush and allowed them to dry.  The result of the treatment was a metallic sheen on the surface of the bark cloth samples, reminiscent of mica, and a slight stiffening of the material.  Checking of the pH of the samples before and after treatment showed that there had been no change in the acidity of the cloth. 

Unaccessioned fragments of deteriorated barkcloth consolidated with sodium alginate solutions of varying concentrations

A second test was run to see if wetting the cloth through humidification could reduce the metallic sheen.  It was hoped that by wetting the cloth first, the sodium alginate would be drawn into the bark cloth, thus leaving less on the surface.  This treatment was successful in reducing the sheen, however, a test of the pH showed that there was still no change in the acid levels and the fabric still retained the slight stiffening see in the original tests.

Overall the experiment showed that this type of treatment may not be appropriate for bark cloth.  This may be because of the structure of the fabric as the beaten fibers lack the directionality seen in woven fabrics and thus move differently.  The lack of affect it had on the acidic pH as well as the metallic sheen and change in handle made the treatment less than ideal for “the black piece” collected by the Forsters.  An object of such importance and rarity should be treated in a way that is safe and will not visually change the object.   In the end, ‘the black piece’ had a custom-padded board and box constructed for it that will allow it to lay flat and be stored safely, in hope that in the future a treatment may be able to stabilize it and preserve it for future generations.'

A mat from Mo'orea

1945.11.130 Mat, Mo'orea

This mat (Museum  number 1945.11.130) from Mo'orea, an island 17km NW of Tahiti, was collected by Joseph Banks on Cook's first voyage (1768-1771), and subsequently given by Banks to Christ Church, his old Oxford college. 

The mat is plaited from hibiscus bast fibres, and is unfinished.  The strips of plant material are very brittle, and unsuitable storage over the years has resulted in several large tears in one corner of the mat.

Tears in one corner of the mat

The conservation treatment on the mat began by surface cleaning using a dry, soft sponge to remove dirt residues.  This was followed by humidification using an ultrasonic humidifier to restore some moisture and strength into the plant fibres.

The tears needed to be reinforced in some way, to prevent further damage which would result in sections of the mat being torn off completely.  The material used was Japanese tissue, a type of hand-made long fibred mulberry paper.  The paper was painted to blend in with the overall colour of the mat, using powder pigments in an acrylic matte medium, and narrow strips were cut which were the same width as the strips of hibiscus bast used to make the mat.  A 'needle' was cut from thick polyester film, and a strip of tissue tacked to the end using superglue.

Weaving a strip of Japanese tissue across the tear

The strip of tissue could then be woven across the tear, using tweezers to manipulate the needle, which was then cut off.

Several strips in place

This was repeated many times, and the ends of the tissue strips were then adhered in place with a paste made from arrowroot starch, which is easily reversible in water should someone in future want to remove the paper strips.  Once one end was securely fastened, the ends strips could be gently pulled to tension then across the tear, and the other end secured with a drop of starch paste.

Treatment nearing completion

There are currently no plans to display this mat, but now it is more stable and less likely to be damaged by handling if required for study by a research visitor.

'A glaring ornament'

Forster No.133 Mus. No. 1886.1.1269

This breast ornament was collected on Tahuata in the Marquesas in April 1774.  Forster, in 'A Voyage Round the World' describes this 'glaring ornament', saying that 'their leaders wore a kind of gorget around the neck, or rather on the breast; it consisted of small portions of a light wood, like cork, glued together with gum, in a semicircular form; a quantity of scarlet beans (abrus precatorius, LInn.) are glued all round it with the same gum, forming a great number of rows, of the length of two or three inches.'

The gorget, known as a tahi poniu, is made up of seventeen sections of wood.  The red and black abrus seeds have been set in a thick layer of brittle brown resin, said to be gum from the breadfruit tree.

Microscope image of gum

As part of this project, samples of the gum were taken and will be analysed by scientists at the University of Bristol.

Sampling from 1886.1.1269

The gorget is missing quite a few seeds - even in 1884 when the collection was transferred from the Ashmolean Museum it was noted that 'many of the berries have come off this ornament and have been stuck from time to time with glue and many are wanting,particularly from the back edge.'  The back of the gorget has been extensively repaired, with new sections of plywood added to replace missing or damaged areas.  This was done before conservation records were kept.

The back of the gorget.  Replacement plywood rays can be seen near the top of the image.

'A Yellow Piece with Red Spots'

This post has been written by Kloe Rumsey, a conservation intern from the Conservation Practice MSc course at Cardiff University.

This large barkcloth, 1886.1.1236 is one of about twenty three pieces in the Pitt Rivers Cook-Voyage collections and is one of three with similar surface designs.

1886.1.1236 Detail

As suggested on the Ashmolean label applied by Assistant Curator Edward Evans in 1886, just before transfer to the newly-opened Pitt Rivers Museum, it is now known to originate from Tahiti and collected on Cook's second voyage in 1773-4. Also bought back to England from this voyage was O'Mai, a man from Raiatea, who, during his 2 year visit to Europe, became famous in high society as the 'noble savage'. 

In this illustration of O'Mai by Nathaniel Dance his barkcloth clothing is of the type worn by those of high rank and it can be seen to include a patterned piece of the same distinctive circular design. The similarities between the garments in this drawing, and objects held in the Forster collections of the Pitt Rivers are striking, and has been noted by then curator Peter Gathercole in the short catalogue to the 1970 Pitt Rivers' exhibition 'From the Islands of the South Seas 1773-4'

The design of this cloth (described in the Catalogue of Curiosities as 'No.15 a yellow piece with red spots') was created by dipping the cut end of bamboo into the dye and applying it to the cloth. Though simple, there is great variation in the patterns and characters created and it is thought that this was the primary method for printed decoration of barkcloths in Tahiti at the time of Cooks' visit.

There seems to have been a dramatic change in the decorative style of barkcloth in Tahiti following European contact.  This cloth a particularly noteworthy example of a very early style, soon replaced by fern printed patterns and other shapes created by the application of painted leaves onto barkcloth.  

Other illustrations of Tahitian barkcloth as garments, as well as the specific description of 'yellow' in the catalogue of curiosities suggests that this, now cream coloured piece has faded from a brighter yellow colour.

Despite the very 'bloody' appearance of this red dye there is no reference to blood being used as a printing medium and it is likely that it is one of the many colours derived from fruits, leaves and bark.

As it can be seen in images from earlier posts these cloths have been stored folded, and, as part of the conservation treatment of this piece it has been surface-cleaned with a conservation-grade soft sponge and humidified to remove damaging creases.  

Creases being flattened with the aid of an ultrasonic humidifier

The barkcloth was torn in a few areas, and the tears were repaired with Japanese tissue and arrowroot starch paste.

Using Japanese tissue and starch paste to repair a tear

This treatment means this cloth can now be more easily rolled around a support and stored safely. 

Barcloth being rolled around a calico covered support

First voyage barkcloth

This post was written by Misa Tamura, our conservation intern from University College, London.

1886.1.1258 (left), 1886.1.1259 (right)

These two fragments of barkcloth were brought back from Cook’s first voyage to the South Pacific between 1769-1771. These pieces were provenanced to the Society Islands/Tahiti, where James Cook, naturalist Daniel Solander and astronomer Charles Green observed the Transit of Venus in 1769.

Tahitian barkcloth, or ‘ahu was typically made from the bark of the paper mulberry, and the breadfruit tree  as well as two types of Ficus. Barkcloth made from the paper mulberry, characterised by its soft, fine quality with white colour, was worn by people of high rank. According to the museum’s records it is possible that these fragments were obtained in Batavia, Java, Indonesia, during Cook's stopover there in late 1770.  The barkcloth was given to Oxford University in 1883 by Captain D.E.E Wolterbok Muller, of the Dutch Royal Navy Service, who had seen other Cook-voyage objects from Oxford at the 1883 International Exposition in Amsterdam.

Beater marks visible under magnification 1886.1.1258 (left), 1886.1.1259 (right)

The fragments appear to be previously stored folded, perhaps in a similar way the to pile of barkcloth in this image from Tahitian section of the exhibition 'From the Islands of the South Seas 1773–4' held at the Pitt Rivers Museum in 1970.

As a result, the objects now have creases along the folded areas. There were also folds along the edges, which were also a result of the previous storage.

After surface cleaning with a gentle vacuum and a soft brush followed by very gentle application of Smoke/Chem sponge, the creases and folds were humidified using a humidifier and Preservation Pencil at 40 degrees Celsius.

After the humidification treatment, the objects were re-housed into custom-made folders made of acid-free card.

The conservation of a kato alu basket

Some of the objects in the Cook-voyage collections of the Pitt Rivers Museum need interventive conservation work, to stabilise them for display or research.  The Tongan baskets which I've talked about in previous posts are examples of this.  The kato alu in particular has been badly crushed in the past, and the palm leaf midribs that make up the framework of the basket have been broken.  The basket has also become distorted, making any repairs even more difficult to achieve.

Discussing the treatment of the Tongan baskets

Before undertaking a treatment, the conservators at the Pitt Rivers often discuss the options. Sometimes, the general feeling might be that an interventive treatment is not necessary, and that with careful packing and handling further damage to an object can be avoided.  Sometimes though, as with the kato alu, something needs to be done to stabilise damaged areas. 

There were two stages to the conservation treatment of this basket.  The first was to attempt to re-shape it, bringing the broken areas back into alignment.  This was done by making an internal support which allowed the basket to rest upside down.  The basket was then humidified, by placing it in a humidity chamber made from polythene and introducing water vapour, produced by an ultrasonic mister. This uses a metal diaphragm vibrating at ultrasonic frequencies to generate very fine water droplets at room temperature.

The kato alu basket, 1886.1.1328 in the humidity chamber

The vapour is absorbed by the plant material, making it more flexible and easier to manipulate.  The basket was left in the humidity chamber for an hour, and was then flexible enough to reshape gently, holding the new position with pieces of foam tied around the basket with cotton tape.

Reshaping the basket

The basket will be humidified several more times, and the foam adjusted until it has reached a shape more similar to the original.  The breaks in the kato alu will be secured on the inside of the basket with strips of Japanese paper, tinted with acrylic paint to tone in with the colour of the basketwork.  In this way, the broken edges will be protected, and the possibility of future damage or losses reduced.