WOAD INDIGO PROJECT - INFORMATION FACT SHEET. 

Woad is a genus of the Cruciferae belonging to the same family as the brassicas, and has many similarities with them. It looks something like a cross between spinach and sugar beet, with many longish green leaves sprouting out of a central crown, so that the plant stands about 40 cm (15 in) high, when fully grown. The woad plant produces two precursors (indican and isatan B) to indigo, the blue dye used in blue jeans and it is important to note that chemically, this natural indigo is exactly the same as the synthetic product. The reason why the woad plant produces indigo precursors is not known and is open to speculation. For example, it has been suggested that it is to prevent insects from attacking the plant, but this is not true, as it is eaten by a wide variety of insects. Other suggestions include, stores for nitrogen, or sugar (carbon), or to enable it to survive in a particular environmental niche, e.g. in the presence of greater levels of sunlight, or ultra violet.

Historically, woad was grown commercially in the UK until the 16th century to reduce imports from Italy, France and Germany. It became a common-place crop right through until the 18th century. Because of foreign imports, mainly from India, it died out as a major crop in the middle of the 18th century. However, it was still grown on a small scale as woad indigo was used to mix with imported indigo in the dye vats to improve the fermentation process.

It continued to be grown as a specialised crop in Lincolnshire until 1932, where it was used to dye military (particularly RAF and navy) and police uniforms. Government cuts at that time resulted in its final demise as a crop, until now, when efforts are being made to re-introduce it into UK agriculture and, subsequently, industry.

This three year project has been funded through a LINK programme between academic partners (University of Bristol and Silsoe Research Institute) and industry, by the MAFF who have contributed almost £300,000, which has been matched by £400,000 from the private sector, viz., Willett International Ltd, Gorham and Bateson (Agriculture) Ltd, Delkor Ltd and Agrifusion Ltd. The objectives of the work are to grow woad on an agricultural scale, using modern farming techniques and this will be coupled to a breeding programme aimed at producing a greater yielding and stable variety of the crop. The woad will be harvested using a specially designed harvester and the indigo precursors will be extracted using a process devised in a feasibility study, funded by the EC. This process is much more efficient than that used in the past and much cleaner. Ultimately, the project will result in the development of a commercial-scale extraction plant. At the instigation of the industry involved, based on the demands of consumers for more environmentally-friendly materials, the end product, indigo, will be used, in the manufacture of water-based, bubble-jet inks for computer printers.

As a consequence of the breeding programme being initiated in this project and the application of modern farming and processing techniques, it is estimated that the European demand for indigo can be satisfied from about 50,000 ha of woad.

The textile and cosmetics markets are searching for more environmentally-friendly products, and fibres, such as flax and hemp are beginning to make a come-back and so, eventually, it will be necessary to provide natural dyes to colour them. We are beginning to take the first steps to satisfy that demand, when it arises.

This project addresses the recognised need for a greater national commitment towards bio-based materials and chemicals. In this respect it will introduce a number of benefits to the economy and environment of the UK as follows:

(i) Although present legislation does not require the immediate replacement of commonly used solvents and colouring matters, it is becoming apparent that some of the less safe chemicals used will not be tolerated in future.

(ii) The agricultural industry is also ready to cultivate the raw materials, on an appropriate scale. This technology will provide an ideal base for further progress towards large-scale production of dyes, pigments and other harvestable molecules from agricultural crops, as well as additional income for the UK farming industry.

(iii) To spur new sustainable agro-industrial development with energy efficiencies and economies, mitigating environmental concerns. Provide a sustainable environment, utilising renewable resources as opposed to non-renewable resources. The detrimental effect of synthetic chemical processes and products on the global environment will be reduced and waste will be disposed of in an environmental and ecologically sound manner by using recyclable and biodegradable processes.

For further information, contact:

Dr K G Stoker or Dr D T Cooke,
Department of Biological Sciences
University of Bristol

Address for correspondence:

c/o IACR - Long Ashton Research Station,
Department of Agricultural Sciences,
University of Bristol,
Long Ashton, Bristol BS41 9AF, UK.
Tel: 01275 549 408
Fax: 01275 394 281

E-Mail: kerry.stoker@bbsrc.ac.uk
dave.cooke@bbsrc.ac.uk