FAQs on Natural Dyeing
1) What is the difference between Mordant and Fixatives?
In the past, dyers understood that natural coloured agents attached themselves poorly to yarn/fabric and would be washed away easily. They discovered that there were assisting agents like alum in case of wool and silk, and tannins+alum in case of cotton and linen that helped some coloured agents (dyes) adhere firmly to yarn/fabric. Before chemical bonding was understood, the dyers imagined that these assisting agents held onto the dye with its hands bit into the fiber with its teeth and held on so as to fix the dye on to the yarn/fabric. The word mordant comes from the Latin root ‘Mordēre’ which means to bite was used to describe these assisting agents.
Fixative does the same job with synthetic dyes and has different methods of ensuring that the dye stays trapped within the yarn/fabric.
2) How do you get the different range of shades e.g. light blue to dark blue?
A single dip in indigo gives a light blue. For darker blues, we re-dip a number of times, with the shade darkening with each dip.
3) How is alum disposed of?
Alum is a natural coagulant and it combined with the tannins, dyes, detergent in the effluent treatment tank and settles down as part of the sludge. The alkaline scouring solutions raise the pH to neutrality and we compost the sludge. It should be noted that the upper part of the Earth's crust is called SIAL (namely rocks rich in silicates and aluminium minerals). The alum in our sludge with time gets mineralized.
4) How do you make alkaline pectinase enzyme which is Eco -friendly and for saponification do you use lye?
We do not scour by saponification as that uses large quantities of lye (sodium hydroxide or caustic soda). Saponification converts the insoluble wax into a soluble soap and removes it. The wax is attached to the cotton fiber via strands of pectin. We have fermentors where we grow microbes that produce enzymes that snip the pectin thereby detaching the wax.
5) Does extraction of madder is often done by dissolving the roots in sulphuric acid?
The red dye from European madder was extracted by many methods.
- The roots and rhizomes were fermented and the extracted red dye was called Fleurs de Garance (flowers of madder).
- The dried powdered rhizomes and roots were powdered and treated with sulphuric acid (2 parts to 100 parts of plant matter) and the extracted red dye was called Garance. After using the rhizomes and roots for dyeing the leftover matter was dissolved in sulphuric acid to produce Garanceux.
- When the powdered dried roots and rhizomes were extracted with alcohol Colorin was produced.
We extract Indian madder only with water.
6) Does sodium hydroxide is needed to produce indigo dye?
Small amounts of sodium hydroxide or lime may be used to adjust the pH to efficiently settle the indigo after the fermented liquor is oxidized. Nothing to be alarmed about.
7) Do Naturally Dyed Garments fade?
The myth that naturally dyed fabrics bleed and fade is still widely held. Our garments have fastness ratings that are on par or better than their synthetic dyed counterparts. However, like all things natural, they need to be treated with care.
Naturally dyed products are good indicators of what is harmful to us.
- Hard water is bad for our hair and alkaline detergents are harsh on the delicate areas of our body. Both these factors, individually or in combination, will add a brownish tone to our neutral greys, earth colours, and yellows.
- Strong sunlight will cause sunburn, it can also tan our yellows, earth colours, and greys.
- Bleach damages our skin, it also lightens fabric colours and weakens the fibers.
- Exposure to acids, alkalis, carbonic acid salts, bleaching agents, heavy metal compounds, chelators, and stains will alter the shade of the garments.
A range of environmental factors can affect naturally dyed materials over time. For example, black slowly ripens in the presence of oxygen. Black yarn should, therefore, be stored in net-bags to allow it to breathe.
Indigo is another dye that is sensitive to environmental factors. Garments that are dyed in indigo are in contact with air containing ozone does fade and acquire a yellow tone that can be washed off. This fading is more pronounced with light shades of indigo. Ground-level ozone is formed by the combined action of light, carbon monoxide, NOx pollution (from vehicle exhaust and smokestacks), and VOCs (evaporated petrol, diesel, solvents in paints, perfumes, sprays, etc.). Hence ozone fading is most pronounced on hot sunny days in a polluted environment. If the indigo garment fades rapidly it indicates that atmospheric ozone concentrations are high. Presently no commercial ozone protectants are available to protect indigo dyed garment. Store indigo garments in air-tight bags from which air has been pressed out.
Note: If you are concerned by the ozone fading of indigo, you should be more alarmed about long-term exposure of your lungs to ozone
“What is bad for natural dyes is also bad for you” is an aphorism that holds most true.