Natural Dyes : where they come from & their pros and cons.
Natural dyes refer to pigments that exist organically and are produced from plants, animals or naturally-occurring minerals without the involvement of any chemicals in the process.
A few of the most popular examples of natural dyes which are sourced from plants include:
Indigo - a blue dye sourced from Indigofera, woad and other plants.
Madder - a red dye sourced from the madder plant. Other natural sources of red dye include Brazilwood and St. John’s wort.
Weld - a yellow dye sourced from the weld plant. Other plants like dyers greenweed produce rich hues of yellow.
Cutch - a brown dye produced from the cutch tree, which is a type of acacia
Natural dyes produced from animals include:
Cochineal - Which is produced from insects that live on cactus.
Kermes - A red dye which is produced from insects that live on the kermes oak tree
Tyrian purple - A purplish pigment produced from a sea mollusc.
Are natural dyes with chemicals still considered natural?
It’s common for chemicals to be added to natural dyes in order to make them consistent and suitable for industrial textile production. When this happens, the dyes are no longer ‘natural,’ because they have synthetic characteristics.
Additionally, some mordants (additives and fixatives used with the dyes), are toxic and can poison the environment, rivers, people and animals if not handled properly. For instance, heavy metals, such as lead, copper and mercury which are used instead in place of natural mordants such as salt.
Chemicals can also be added during growing and harvesting of plants making the dye ‘inorganic’. For example,
Using pesticides, herbicides, and defoliants to treat plants
Extraction methods involving chemicals. For instance,
- Sulphuric acid is used for extracting madder from plant roots
- Lye and sodium hydroxide and used during production of natural Indigo
Reasons why natural dyes are not widely used
Natural dyes are preferred because they occur naturally in nature they have a pleasant natural smell and rich appearance; 100% natural dyes, unlike synthetic dyes, don’t contain non-biodegradable chemical additives which kill plant and aquatic life; Natural dyes are also safer in the home environment.
But even with these positive qualities, natural dyes are not used as much as they should be, for the following reasons:
1| Inconsistencies in quality
Due to differences in soil ph. values and unpredictable weather patterns, the quality of dye extracted from plants can not be inconsistent. To achieve consistency, the plants need to be grown in a controlled environment.
This approach is impractical, given the high amount of dye required for mass production of textile. There simply isn’t enough space to grow enough plants to produce enough dye for large scale textile dying. As such, today, 100% natural dyes are used for handicraft production of textiles in small scale.
2| Some dyes have naturally occurring substances that are poisonous
Extra caution should be exercised when using natural dyes especially at home, because even if they are natural, they may not necessarily be safe and can have the following effects:
Hematin and hematoxlyn, contained in logwood, a naturally occurring dye, is very poisonous and should not be inhaled or absorbed through the skin
Indigo irritates the eyes and the respiratory system
3| More water is required when using natural dyes
Dyeing with natural dyes uses more energy as the dye baths have to be kept very hot for long periods. Synthetic dyes are optimised to overcome these challenges.
4| Natural dyes fade when exposed to light and also wash off easily
To make the dyes less wash-fastness, they are treated with mordants. Though natural mordants such as salt and pomegranate can be used and have been used historically, these do not attain complete fastness. Even natural mordants such as alum(aluminium), though considered safe, are still toxic.
5| You cannot attain a wide range of hues and shades using natural dyes
Synthetic dyes on the other hand, can result in endless hues, including mimicking those of natural dyes. Since it’s important to replicate a wide array of colours in manufacturing, synthetic dyes are more acceptable in the process.
6| Textiles dyed with natural dyes are more expensive
This is because:
It takes a large quantity of dye stuff to colour a fabric to satisfaction
It takes a lot of time to grow the plants from which natural dyes are extracted
It also takes long to get good results when using natural dyes as the process takes two times longer than when using synthetic dyes
It takes a lot more natural dye to colour a fabric than it does synthetic dye
This calls to question the ecological soundness of natural dye. If used for commercial dyeing, it would mean the depletion of natural resources as the trees, plants, animals and minerals from which the dyes are sourced cannot be replenished faster than they are harvested.
How more use of natural dyes can be encouraged
To promote the use of natural dyes, research needs to be performed to make their production more efficient and sustainable for large scale fabric dying. Some producers of dyestuffs are already spearheading these efforts, and have made some breakthroughs.
In 2008, the Global Organic Textile Standard (GOTS), which approves dyes and fabrics that are completely organic, approved natural dye extracted from madder, which handles better, is colour-fast and is efficient to use without adding any chemicals.