Quick Dips

Restoring Taonga

New technologies are being used to restore old fabrics -- traditional woven harakeke taonga (flax treasures) that are fading and falling apart.

Unlike undyed fibre, which is comparatively stable, these artifacts have been dyed black by the traditional Maori process and are badly degraded. The fibre has lost strength and the colour has faded.

It's a problem which is being tackled in a project involving Industrial Research Ltd, Carina Chemicals and Rangi Te Kanawa, a leading textile conservator specialising in Maori weaving. It is being assisted by the Public Good Science Fund and supported by prominent Maori weavers and the Scientific Department of the British Museum.

IRL researcher Dr Gerald Smith says the loss of Maori heritage concerns both Maori and museums that have such antiquities in their collections.

"We are aiming to slow this degradation and, where the damage is extensive, find a method of consolidating the fibre," Smith says.

He says the problem is with the dye, which is an iron-tannin complex with the iron derived from paru mud and the tannin usually from hinau bark or manuka/kanuka bark. It is this dye that is responsible for the degradation of the fibre.

Smith says several novel gel-like reagents have been tested for their efficiency in strengthening the fibre.

"One of these has given promising results by preserving the mechanical integrity and handle of the fibre, and showing no visible alteration to the appearance of the fibre as assessed by experienced textile conservators," Smith says. "This material, applied to aged fibres, has also improved the integrity of these fibres."

In the laboratory the fibres are artificially aged by thermal treatment (heating at 80^oC for a month) or irradiation with simulated solar radiation.

Smith says ageing experiments using controlled and limited oxygen supply indicate that oxygen is important in the degradation process.

"We are conducting experiments monitoring the consumption of oxygen during thermal treatment," he says. "It is possible that degradation may be stopped at an early stage by sealing black fibres in air-tight containers."

Preliminary work on fibres containing different iron contents also indicates the rate of degradation is increased in wet air by increased iron. A systematic study of this is now in progress using different tannins and controlled amounts of iron.

The research has also discovered a novel method for finding the place of origin for ancient black-dyed taonga.