Questions asked during the presentation are given below with what can only be short answers to very complex issues in many cases. The answers are provided by the SDC.

What do you consider to be the most sustainable /eco friendly dyed fabric options/ combinations currently being used?

There is not one best option available as there are too many variables including source of fibre, source of dye, application of dye, fastness in use, reuseability/ recyclability. Each of these topics could be broken down further and is also not an exclusive list. This provides a really difficult situation for many individuals and companies. The lack of clarity in areas such as life cycle analysis for various combinations creates a raft of different perspectives. Is wool more sustainable than cotton? cotton more sustainable than polyester? Cotton – where is it produced and under what conditions, it also uses a lot of salt in the dyeing process but not everything has to be dyed batchwise, polyester is hydrocarbon based so raw materials sourced from the petrochemical industry and requires high temperatures to dye – but it can be dope dyed while being extruded and it plus currently associated with microfibres. Viscose has a bad reputation so we move onto Tencel but it can’t be used in all circumstances due to the inherant properties plus it is dyed with reactive dyes like cotton and so uses a lot of salt.

The best advice is to understand the supply chain – source of fibre, source of dyes (think labelling schemes, RSLs and MRSLs), application of dyes (best practice as taken up by many dyeing companies in the world is a lot less water intensive and environmentally polluting than the media would have you believe) plus effluent treatment and their effective use and specify the fabric properties accurately to create a garment that last and can be recycled.

Do you consider the use of natural dyes sustainable / eco friendly for current designers?

The use of natural dyes for the coloration of textiles has its place but will only ever be a niche and very small percentage of the colorants used because of the one fundamental issue – the use of land for growing non edible crops. Associated with this is the sheer volume of plant material needed to create the large quantities of dyes required.The use of mordants is another potential issue as there may be restriction on use in bulk situations.

This statement however makes an assumption that natural dyes are plant based and have to come form sources as in days gone by. Potentially non plant based dyes or alternative sources of either coloured or non coloured starting materials reduces the dependancy on the petrochemical industry, modification of existing colorants from non traditional sources may have a role combining the natural with the work of a chemist.

Her are links to three papers that have appeared in Coloration Technology on the subject, 1993, 1997 and 2008. The topic of natural dyes in a commercial environment have been considered for many years and yet no viable route to this has been achieved to replace synthetic dyes. Maybe the next few decades will provide an alternative source of colorants.

Are Natural Colorants Good for your Health? Coloration Technology, Glover 1993

Natural Dyes – Review of Progress in Coloration (part of Coloration Technology), Hill 1997

Doing what comes naturally in the dyehouse. Coloration Technology, Glover 2008

Is woad and indigo same?

Woad is obtained from Isatis tinctoria, also called woad, dyer’s woad, or glastum. Indigo is obtained from Indigofera tinctoria. However both plants produce colour through the same entity which is indigotin therefore both produce their colour through the same means while the source is a different plant. The major difference appears to be the concentration of indigotin in the plant material. Woad is less concentrated in indigotin than Indigo itself is, meaning more has to be used, which is presumably why Indigo started to become more popular than woad in Europe in the 16th century, after it was introduced from Asia.

Dyes in health care which you showed are practically used in industry?

Dyes are used in many areas of healthcare. The use of dyes in photodynamic treatment is continuing to be researched and being considered for use following the usual protocols of treatmetns being approved.

Can bacteria produced dyes be a way forward and can dyes be recycled?

Alternative sources of dyes are being researched around the world. Bacteria are just one of many and interest in this area is growing. Companies who are increasing their activity in this area are Colorifix and Pili as well as Post Carbon Lab. A search on the internet will provide more information.

Research into dye recycling is ongoing. Removing a product form a fabric while maintaining its integrity as a coloring matter is the main issue if you require it to be able to function in the same way it did before application. We are unaware of anyone who has commercially launched a range of recycled dyes.