Traditional dyeing methods are as old as the hills, but with time and the advance of new technologies, petrochemical alternatives began to emerge, which were deemed easier to control and stabilize to better stand up to washings, light and rubbing. Today, a desire to steer clear of fossil-based compounds is renewing an interest in natural, time-tested processes. Are plants finally having their day?
Just as petrochemical synthesis continues to be perfected, natural dyes and pigments have also been the focus of ongoing research. Given the desire to adopt a circular approach, every product is closely scrutinized so it can be put to maximum use. Roots, barks, algae, skins and peels can be converted into coloring agents, and food waste is proving to be a valuable dye resource. Some of these raw materials also possess other intrinsic properties, such as being antibacterial.
Once frequently used in natural dyeing processes, pre-treating fabrics with metallic mordants, which are highly toxic, is now being abandoned in favor of using bio-mordants such as aloe vera or tannic acid, and technologies such as ultrasound, which can also help fix color more easily in the fiber.
Some natural dye ranges can be developed at lower temperatures, saving considerable energy. Temperature and pH variations also help some dyes, such as indigo, to be developed in a wider range of colors.
Limitations to consider
The fact that they’re natural does not mean all naturally dyed materials are free of toxic risks. Plants can also contain molecules presenting an allergenic, mutagenic or carcinogenic risk. Their molecular structures and concentrations in products have to be analyzed, and must be screened by regulations such as Reach to ensure their safety.
Another important issue is whether these natural resources can be developed on an industrial scale. By making use of the resulting co-products, the process is intrinsically virtuous. However, if developing such resources means allocating agricultural lands, then they’ll be competing with food resources, and subject to the same climate uncertainties, potentially weakening supplies.
Another possibility: don’t dye and instead take advantage, for example, of the natural colors of some specific cotton varieties, which are naturally found in shades of pink, orange, brown or green.