What are Natural Dyes? How is it prepared? How is it better from Synthetic Dyes?
These are questions that hits first when we talk about Natural Dyes. And the answers to these questions are not complicated as you think. There are lots of things that nature have already given us and we've been lifting the beneficiary out of it since time immemorial and until today we all depend on nature for our survival. Nature not only provide what we need but also beautify our needs in several ways and dyes given from different parts of the plants are one of them. We all know dyes are pigments or colours applied on a material, be it on fabrics or foods or our body parts like hairs for better looks. In other word, dyes are like cascading style sheets that design materials for more attraction.
Marigold
Beetroots
Henna
Morissa
Preparing natural dyes depends on the plant's part we're opting to proceed extraction. Generally the part of a plant for example marigold's petals are taken and dried, they're then crushed into fine powders and mixed in a solution (if it is distilled water, we take 3.3 gram in 100 ml of distilled water). The solution can be of either methanol, hexane, acetone or simply aq solution in appropriate ratio with samples. Now here comes the interesting part of extraction. We can either give the solution in a shaker for 48 hours or we can use soxhlet extraction method to extract dyes.
Leaves of Henna and Morissa are are usually picked for extraction of dyes and same procedures are followed and Beetroot is sliced into thin parts and dried. The same procedure is followed afterwards.
Filtering out dyes
Mordants used
Extracted dyes from Beetroots, Marigold, Morissa and Henna
Synthetic dyes are those that are prepared in industries using different type of chemicals. It has significant features but has many disadvantages.
~ The chemicals in preparing synthetic dyes are highly toxic and carcinogenic or even explosive.
~ The chemicals used in preparing dyes are mostly allergic to skin, hence skin rashes is common to people wearing clothes dyed with synthetic dyes.
~ The dyes usually washed off and caused pollution because of the toxic chemicals present in them.
Natural dye on other hand are skin friendly with no allergy or skin rashes. Since it is purely extracted natural products it has less side effect and also it's pigments doesn't washed off that easily. The most important part is, they have anti microbial agent which when clothes dyed with natural dyes are worn, there are chances of less microbial infections.
How fabrics or yarns are dyed with Natural Dyes?
Fabrics and yarns are well prepared before it's proceeded for dying. They are well soaked in different mordants such as Ferrous Sulphate, Copper Sulphate, Potassium Dichromate, Potash Alum and Stannous Chloride. The reason is for the dyes to last longer on the yarn or fabric. The mordants are prepared in appropriate ratio that is 1:40. For 1 gram of compound mentioned above, 40 ml of distilled water is taken to prepare the solution and they're heated at 50 degree celcius for half an hour. The fabric or yarn are then dipped in them and incubated for another half an hour at 85 degree celcius. The fabrics or yarns are then taken out and squeezed and washed them with tap waters and dried at room temperature. After it was dried, the fabrics or yarns are immediately taken for dyeing. We compare the fabrics or yarns that are dipped in different mordant and picked that are best dyed.
Dyed fabrics
I worked on this project from march 2019 to march 2020 along with my friends "Rajesh Adhikary, Shrutasrini Hazarika, Animesh Sharma, Marngam Bam" with the help of our subordinate Dr Sony Kumari Ma'am who's also Associate professor and Head of Department in Applied Biology, University of Science and Technology Meghalaya.
Special Thanks to these young scientists.
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