Rights: Scottie Productions Published 17 December 2015 Download

Rangi Te Kanawa, a textile conservator at The Museum of New Zealand Te Papa Tongarewa, faces the problem of rapid deterioration in dyed harakeke artefacts such as garments and mats. In order to ensure these precious taonga survive, she worked with Dr Gerald Smith from the School of Chemical and Physical Sciences at Victoria University and Landcare Research staff to analyse and to develop an innovative new conservation method.

Point of interest

In this clip, Rangi Te Kanawa and John Campbell talk about the breakdown of harakeke. They explain that harakeke has high hemicellulose content, and this compound produces acetic acid when it breaks down. Acetic acid further accelerates the breakdown of the harakeke artefact that produced it, and being prone to vaporise, it can float off and affect other exhibits or stored items. In the museum environment, this is referred to as ‘vinegar syndrome’.


Dr Ocean Mercier

Māori have always been scientists, and we continue to be scientists. Our science has allowed us to live, work and thrive in the world for hundreds of years. My name is Dr Ocean Mercier, and I’m a lecturer in pūtaiao Māori at the Victoria University of Wellington. My job takes me all over the world to talk about Māori science and how traditional knowledge is being married with western science here in Aotearoa in order to find innovative solutions to universal global issues.

In this programme, we’re going to show you how these worlds of science are intersecting and how the paths to our future are being formed.

Traditional uses of harakeke were numerous. Twisted, plaited and woven, it was used to make fishing nets and traps, footwear and ropes as well as whāriki and kete. The roots were crushed to make poultices for skin infections. The gum from the base of the plant was used to help heal wounds. Muka, or flax fibre, was extracted to create incredible textiles.

The amazing artistry and knowledge of our tūpuna can be seen in public and private collections all over the world, but today, conservators are seeing some of these taonga disintegrating through age.

Ko Te Papa i Te Whanganui-a-Tara, te whare pupuri taonga o te motu, ā, kei roto i a ia te kohinga taonga kākahu Māori nui rawa o tēnei whenua. (Te Papa in Wellington is New Zealand’s national museum and holds a large collection of Māori textiles.)

Ko te rapu tikanga tiaki i ēnei taonga, te whainga matua o Rangi Te Kanawa, te kaitiaki taonga kākahu Māori kotahi o te motu, e heke mai ana i te whakapapa kaikotu. (Finding a way of preserving these taonga is a passion for Rangi Te Kanawa, New Zealand’s only Māori textile conservator and comes from a long line of weavers.)

Rangi Te Kanawa

We’re in Te Whare-Pura, this is the Māori textile store in Te Papa Tongarewa. We house approximately 400 cloaks. It’s the largest collection of Māori textiles in the world.

My responsibility as a conservator is to provide best storage systems and conserve/treat any of those taonga that are needing conservation.

To do that, we need to know how the textiles are made up and what materials they’re made of and how stable they are and what’s caused them to deteriorate and the best means of retarding that deterioration.

So as a conservator, you know, stabilising them and making them exhibitable and caring for them in their collections is a priority to me. It’s a great profession, and I feel for Māori textiles, I have a huge admiration for their craftsmanship.

I’ll just show you a variety of kākahu in our collections. This is a kahu kiwi, and it is a kākahu completely adorned with kiwi feathers – so it’s really quite pretty, and its woven onto a base of muka.

The next one here is a kahu kurī, and this is considered to be the most prestigious of our cloaks. It is again woven with muka on the base and the kaupapa, and it’s adorned with strips of the dog fur that accompanied our tūpuna from Hawaiki to Aotearoa. So a very prestigious cloak and worn mainly by our rangatira.

The next one is a korowai. I often hear people refer to their kākahu as a korowai – every cloak seems to be a korowai – but in actual fact this technically is the korowai. It’s a cloak that’s got the black thrums on it. It is our biggest problem in Māori textiles is that the stability of the dyed black fibre, because of the traditional method of dying it. It’s very acidic, and so you get fragmentation. You can see actually there’s a lot of fibres here on the card that’s holding the korowai. It’s not a good feeling because we lose so much of our intellectual property, you know, the thought and all the creation that went into making our kākahu of those times. And they’re unique. It’ll be very difficult to get a weaver today to reproduce something like this. So we don’t want to lose that, because once that’s lost, that’s it.

Dr Ocean Mercier

Kei te Whare Wānanga o Wikitōria a Gerald Smith, ā, ko tōna tohungatanga, ko ngā āhuatanga matū e whakararu ana i te oranga o ngā rawa paraumu. (At Victoria University, Dr Gerald Smith specialises in the chemical and physical processes responsible for the degradation of organic materials.)

Kei te mahi tahi a Rangi rāua ko Gerald ki te turaki i ērā momo raru. (Rangi and Gerald have forged a working relationship to tackle the problem.)

Dr Gerald Smith

One of my main subjects that I teach is a course in heritage material science, which covers all about the protection, the preservation of all sorts of heritage objects. And of course, one of the most important of these types of materials that we’re studying in this course is the degradation of Māori weaving.

The problem being that, when harakeke or muka fibres are dyed black in the traditional Māori way, they degrade over time, and they lose their strength, the fibre fades and it’s a major problem. And of course, one of our big aims is to try and find ways that we can protect the fibres and slow down this degradation. But to start this, we’ve got to understand what’s going on.

Rangi Te Kanawa

This is the warrior’s cape. It’s been dyed black in the paru, and it also shows signs of fragmentation. You can see there’s some elements that have become lost from the kākahu.

The main issue, it’s quite serious, is the deterioration or breakdown of the traditionally dyed black fibre, and that is because it’s quite acidic in its nature. But before the fibre is dyed black, it has an inherent problem anyway. It has a very high content of hemicellulose, and that produces acetic acid.

Dr Gerald Smith

And we know that, once acetic acid is being produced, it just gets the ball rolling, and it catalyses more and more degradation. So we’ve got this real focus on acetic acid. We’re trying to slow … find ways of, well, firstly what causes the acetic acid to be produced and then how can we sort of either neutralise the acid or slow down the production of the acetic acid.

Rangi Te Kanawa

When I began my training as a conservator, I realised then that there was a problem – a problem that I’d been witness to as a child, watching mum and nana put this fibre muka into mud.

And so you know, I can remember talking to my course convenor at the time and saying this is a huge problem, because I envisaged that there would be issues around the type of mud, the type of tannins used to pre-treat it before it goes into the mud and then, you know, that was all confirmed when I actually came in to take up my role after training, to take up my role as a conservator.

Dr Ocean Mercier

Rangi Te Kanawa had recognised the problems that museums faced dealing with harakeke from her days as a conservation student.

By combining mātauranga accumulated over generations within her whānau with cutting-edge chemical science, Rangi hoped her and Dr Gerald Smith could develop a process that would arrest the degradation in ageing harakeke textiles.

Textile conservator Rangi Te Kanawa had been struggling with the degradation of ageing harakeke textiles within museum collections, especially those coloured black with traditional mud-dying techniques.

In order to arrest the decay, she had turned to scientist Dr Gerald Smith to see if they could develop a new conservation method.

Kia whai ai rāua i te harakeke, i tahuri ai a Rangi rāua ko Gerald ki a Manaaki Whenua i Otautahi, te papa kāinga o te whānau harakeke. (For their supply of harakeke, Rangi and Gerald turned to Manaaki Whenua in Otautahi, home to country’s largest collection of cultivars.)

Sue Scheele

Well, this is the National New Zealand Flax Collection at Manaaki Whenua Lincoln. There’s a whole range of plants here. We’ve got plants from all over New Zealand, and a lot of them are very special weaving varieties that were collected in the 1960s and 70s by Rene Orchiston.

Katarina Tawiri

So there’s obviously different cultivars used for different purposes, some are good for kete, some are good for mats, some are good for muka.

Sue Scheele

This tall, somewhat droopy variety is called māeneene, and it was a real favourite in the Urewera particularly for making whāriki. Although it’s droopy, it’s quite a strongish leaf, so OK for making and weaving mats but not very good for extracting muka.

Katarina Tawiri

So here we have the parekoritawait has a lot of muka in it. Although a lot of people considered the variegated ones, which are these striped flaxes, not to be very good muka ones or even weaving ones, they are actually good, and they make really interesting little ketes, because when they dry, you can still see the stripes slightly so it makes a nice effect.

Sue Scheele

We’ve worked with Gerald for a lot of years on different projects about harakeke, and for this particular one, he wanted supplies of muka from our very best plants.

The first one is makaweroa, and that’s probably one of the best muka varieties of all – very long, very strong, very white.

Here’s a flax leaf that looks really just the same as the makaweroa. This one perhaps feels a little firmer, but you know, if you saw the bushes, you’d think they were exactly the same. But as Katarina will show you when she goes to extract the muka, really they behave very differently indeed.

Katarina Tawiri

Take the mid rib off. Just strip it out like that. And you can already see lots of green stuff of the leaf is sticking to it. Then I want to do the extraction, and voila, no strength and the fibre rips off straight away.

So, we look at makaweroa. The name tells you ‘makaweroa’ – long, long hair – so that’s, that’s a perfect name for it.

This is one of the cultivars, which are harvested and sent up to Rangi and Gerald. And I actually sent up quite a lot of it, and I extracted it all by hand. Here you will see that you can actually extract the whole length of the leaf. There you go, and then you only got what’s called the para left on it, and you can just kind of very easily get rid of that. Yep, there you go, beautiful white fibre. And this was used for their project on the cloak preservation.

Dr Gerald Smith

We get our fibres from Sue Scheele – Landcare Research. They hold the national collection of harakeke. There is a national collection, and it houses about 30 different varieties. And we only work with the same variety each time, so we have the same sort of genetic material to work with.

These are the fibres as they’re stripped out of the harakeke leaf. As you can see, this particular variety is very white. But they all produce the substance acetic acid, better known as vinegar. And it’s a breakdown product. Although it’s not present in the fibres as they exist as they’re fresh, as they age and breakdown, they produce this acetic acid.

In terms of this project that we’ve been working on, it’s the black-dyed fibres that are the most degraded. And the way the Māori traditionally dyed black was to soak the fibres. Here I’ve soaked these fibres in a solution of tannin derived from the bark of hīnau soaked in water.

And the great trick is that, once treated with tannin, it’s then treated with iron. Now the iron in this particular case came from a mud called paru. And in the laboratory, we’ve simulated this – we’ve got a solution here of ferric irons that just come out of the bottle. But if I dip these tannin-treated fibres, almost instantaneously, you can see this intense black colour, and this is the iron tannate dye. It’s the iron that’s causing so many of the problems.

The whole aim of this research is to try and find what firstly increases the amount of acetic acid being produced and secondly what treatments might we do to reduce that amount of acetic acid.

Rangi Te Kanawa

Because of the acidic nature of the whole colouration process, the fibre just breaks down, it fragments into a powdery mass, and when it does that, we have a loss of the woven matrix, and elements become loose, and then eventually there’s a collapse in the weave and there’s also a loss of the construction work. So technically, we can’t refer to it, because it’s all been – its collapsed. So it’s serious, and for a few years now, we’ve been studying the mechanism of the degradation, and working with Victoria University, we’ve engineered a consolidation treatment using sodium alginate.

Dr Gerald Smith

Rangi has been, being a conservator, has been working on a consolidant. That’s a material that, once the fibres start to fall apart, the conservator’s job/task then is to consolidate or stick the fibres together. She’s been using a novel consolidant that she’s developed or that we’ve developed in the course of our research. It’s extracted from a seaweed. It’s called alginate.

Dr Ocean Mercier

Kia mōhiotia ai te hua o te tauārai tote waikawa ki te whakaheke waikawa winika i te harakeke, ka kokoia, ka ahutia te muka. (To test the effectiveness of the alginate consolidant in reducing acetic acid, the team dye and treat the harakeke fibre.)

Dr Gerald Smith

And the way we find out whether our treatments have been effective or not at producing acetic acid or reducing the amount of acetic acid is we put our treated fibres in a sealed vessel. It’s got a septum in the top so that we can extract samples at various intervals with a hypodermic needle. And the way we speed up the ageing process is we put it in the oven in our laboratory at a set temperature. So we’ve been very interested in detecting under accelerated ageing conditions.

In this experiment, we’ve treated the samples with alginate to see whether the alginate neutralises the acetic acid being produced. And we use this hypodermic needle and put the hypodermic needle through the septum in our sampling vial. The gases are absorbed in this needle and then we withdraw the gases and then we transfer it over to the gas chromatograph and then we insert the needle in the gas chromatograph and we inject the sample. This instrument will separate out the various components and tell us how many – how much acetic acid is being produced and whether the alginate treatment has reduced the amount of acetic acid produced.

Dr Ocean Mercier

Textile conservator Rangi Te Kanawa and Dr Gerald Smith had been working together to preserve harakeke textiles and had developed a treatment they thought could work. By reducing the acetic acid they would reduce the degradation, but whether it would work outside of the lab was a question that still required answering.

For Te Papa Museum in Wellington, holder of the world’s largest collection of Māori textiles, the degradation of harakeke items was a huge concern. Rangi Te Kanawa, their textile conservator, had developed a chemical treatment with Dr Gerald Smith that they believed would nullify the degradation.

With many items in the museum’s collection showing signs of deterioration, the need to protect these taonga from the ravages of time was critical.

Rangi Te Kanawa

OK, so this is a kaitaka paepaeroa. This one shows a good example of the deterioration of the black, because you can see here the loss of the black, and just the weft threads or the aho threads remain in between the brown there.

So here we have an example of the loss of the black fibres, so because of the loss, it’s completely made the other elements that it was woven over exposed and a lot more vulnerable and so the treatment for this was to consolidate the black and then support underneath and just secure those loose elements into place.

Dr Gerald Smith

Now this is the sample that we’ve treated with alginate, and you see this peak here is the peak showing the acetic acid. However, when we compare this with the sample without treatment with alginate, here’s the acetic acid being produced again, but this time, there’s very much more acetic acid. And this was really a breakthrough as far as we’re concerned. It demonstrated immediately that the alginate provided some protection to the black-dyed fibres by presumably neutralising the acetic acid.

So now with this finding, it has some immediate application in terms of conservation in museums, and Rangi Te Kanawa is now using a nebuliser to produce a very fine spray of this sodium alginate, so she can actually treat cloaks that have been black dyed in the way I’ve described and hopefully protect them against further damage or at least slow down the damage that they are experiencing at present.

Rangi Te Kanawa

This is a cloak – a korowai – that has been treated with the sodium alginate, and we’ve applied it as a consolidation treatment. So it doesn’t alter the colour significantly, it doesn’t provide any flexibility, but we are accepting of that. What it does is it is just maintaining those fibres and binding them together, as well as the main property of its performance is to reduce the production of acetic acid.

Dr Gerald Smith

We know that the alginate neutralises the acid being produced by the fibres as they degrade. So this is a really quite exciting development in the museum scene.

Sue Scheele

Well, I think for both of us actually, one of the biggest pleasures is working on projects like we are with Gerald and this cloak preservation. And it’s just fantastic to think that the muka that we provide from here is going up to Wellington to be processed in the lab for Gerald and Rangi to look at that and do their workings and find out a way to preserve these wonderful cloaks, and we really hope that this is going to work well.

Rangi Te Kanawa

And the future for Māori textiles that are made from traditional times, particularly because they possess the traditionally dyed-black fibre, we’re limited with how much we can handle them. If they’re not treated ,they’ll fragment. So if we hadn’t engineered a consolidation treatment, things are quite limited, very limited actually. So they’ll just continue to deteriorate. So I’m quite pleased that we’ve finally got the results we want. I still think there’s a lifetime of research to go, we do have to look at all the different varieties of harakeke and how well they retain the colour or don’t retain colour or how stable they are or unstable they are, the different dying traditional dying methods. Yeah, there’s still a bit of work to go.

Dr Gerald Smith

Black dye is one of the most interesting things I find is that this black dye, this iron tannate dye, has been used by civilisations since the ancient Egyptians used it on papyrus. They get their raw materials from slightly different places, but chemically, it’s exactly the same dye as the Māori used. So it’s a very widespread problem, so what we can find out studying the Māori fibres can have quite wide implications in all sorts of areas where it’s been used by different civilisations.

Dr Ocean Mercier

By developing a solution to a problem that threatened the stability of harakeke textiles, especially those dyed black using the traditional paru method, Rangi and Gerald had uncovered a solution with wide-ranging implications.

With the harakeke textiles in the collection now being treated, their lifespan has been increased dramatically, and for textile collections around the country, it’s a treatment that’s easily replicated.

With many other indigenous cultures using chemically identical dying methods, their work could be utilised by conservators around the world.


Video courtesy of Scottie Productions.
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