Dyes & Finishes for fabric and fashion

.....looks like Chemistry, ah..... this is quick outline of the key dyes and finishes to avoid... avoided anything that is in the bold.

Polyester is dyed with disperse dyes, small molecules penetrate the fibre and are fixed through a variety of electrostatic interactions. This results in a degree of migration out of the fibre, leading to the high incidence of contact dermatitis and allergic reactions.

Dying polyester and polyester blends requires dye carriers that aid dye penetration. These are generally carcinogenic.

Dyed cotton uses Reactive Dyes. These chemicals bind with the garment fibre and leave up to half the dye in the water after dying. These chemicals are hormone mimicking and harmful to aquatic wildlife.

Azo group of dyes covers about half of all dyes currently used. Made from nitrogen bond, these give molecules their colour under reductive conditions; they can form amines. Some have been shown to be carcinogenic and 22 are prohibited by the EU. Benzidine-based direct dyes were found to be carcinogenic over 30 years ago and implicated with bladder cancer in textile worker, yet a large number of manufacturers in Asia still use them.

Salt used to even out dye colour is discharged into waterways making soil too alkaline to crop.

Optical Brighteners are chemicals that reflect light, making your clothes look brighter than they actually are. In clothing manufacturing, they are used after the bleaching process to resolve any colouring unevenness. Many optical brighteners are made using stilbene, which is toxic to fish, and can cause allergic reactions when in contact with skin.

Bleach is used in preparations for dying or to produce white. The 2 most common methods of bleaching use Chlorine-based bleach, or hydrogen peroxide. Hydrogen peroxide is non-toxic but cost much more than the chlorine-based process. Chlorine-based bleach is toxic in high concentrations and there are concerns that subsidiary reactions lead to the production of a range of AOX (absorbable organic halogens) including trichloromethane and dioxin precursors. This

Textile Printing involves the application of a colour paste, made up of dye and a thickening agent and other chemicals onto fabric. Sports shirts use PVC, which is not biodegradable. PVC needs Phthalates to soften it up and these are suspected sex change chemicals and carcinogens.

Chemical Finishing is a process of treating clothes with chemicals to give them a desired property. A ‘finish’ can make a garment softer, shrink resistant, crease resistant, as well as providing properties such as anti-microbial agents to prevent sports and undergarments developing odours.

Mothproofing (for wools) the most common chemical is Permethrin, which is a nerve agent and toxic to aquatic species.

Flame Retardants can be toxic, non-biodegradable and have suspected or proven health risks depending on exact chemistry. Exposure in the womb to polybrominated diphenolethers has been associated with abnormal skeletal and brain development in animal testing.

Conventional leather processing begins with preservation using salt as soon as the skin comes off the animal, cleaning to remove hair and unbound proteins in the skin. The next state is tanning. 90% of the leather of the world is Chrome tanned. Chrome III is safe. Chrome VI is NOT safe and is carcinogenic. In elevated temperatures Chrome III can oxidize and convert to VI. Thus too high temperatures, leaving it moist for too long and not biding the chrome into leather will leave Chrome VI in the leather and in the wastewater as well. In addition, some fear that in landfill it could leach.

Polythurethane (PU) coating can also be used as a final finished to cover faults from animals scratching etc.

Wool processing using harsh scouring agents, bleaches, energy and a huge amount of water. Non-ionic detergents and inorganic salts are used to emulsify grease. Most wool is dyed with Chromium-complex dyes. Short-term exposure could cause allergic reactions to skin, breathing and the stomach. Long-term exposure or ingestion can cause kidney and liver damage.

Note:

While most of these chemicals will never effect the wearer of the clothes, I can understand the caution of pregnant woman and mother’s of babies who turn to organics at that stage of life.

The major victims of these chemicals are

1) the workers in Sweatshop with no precautions, knowledge and working under stress and

2) the environment where the wastewater is pumped and the local people and animals

We should ask ourselves whether it is a coincidence that in regions of the world that produce PVC we hear news stories of 7 year old girls giving birth and in other areas of the world with highly polluted waterways from factories and cotton fields (where pesticides designed to attack the reproductive systmes of insects are washed into) babies are being born with mulitple limbs and heads. This is just speculation, something to think about and I think to be investigated.

Most of the information above is based on information from the book SUSTAINABLE FASHION & TEXTILE by Kate Fletcher (earthscan, www.earthscan.co.uk)