Introduction:
Dyes are coloring materials. They are either soluble in the dyeing medium (e. g. water) or can dissolve into the textile substrate. Dyes are used in many industries – in textile, paints, plastics, photographs, prints, and ceramics. They are designed to bond strongly to the polymer molecules that make up the textile fiber. There are different types of dyes such as reactive dyes, disperse dyes, direct dyes, azoic dyes, sulphur dyes, vat dyes, metal complex dyes etc. Before going to comparison we should know about reactive dye, azoic dye and vat dye. I have just given an introduction ob above three types of dyes.
Reactive Dyes:
We have published lots of article on reactive dyes. But giving comparison among dyes I have summarized about reactive dyes. Basically reactive dyes react with fiber specially react with cellulosic fiber such as cotton, jute, bast fibers, viscose, flax etc. Reactive dye contains reactive groups and this group makes covalent bonds with fibers which become part of fiber. This is the type used in the home and at schools and known by the trade name Dylon.
You may also like: Reactive Dyes: Classification, Dyeing Mechanism, Application & Stripping
General structure of any reactive dye can be presented as follows:
W – D – Q – RG – X
Where,
W = Solubilized group
D = Dye chromophores
Q = Bridging group
RG = Reactive group
X = leaving group
Azo or Azoic Dyes:
Azoic dyes are not ready-made dyes but are produced by reaction of two components those are Diazocomponent or Base/Salt and Coupling component. The colored substance formed azoic dye from these essentially colorless compound is insoluble in water and the washing fastness of the shade is excellent. However, these dyes are not eco-friendly; some of the dyes, when they break down, become carcinogenic. Azoic or Azo Dyes are used on cotton, linen, viscose and lyocell.
Vat Dyes:
The word “Vat” means Vessel. The dye takes their generic name from vetting. The vat dyes are insoluble in water, thus can’t be directly applied and required vetting. Among all the dyes, it has the best fastness properties. Vat Dyes are used for cellulose-based fibers: cotton, linen, viscose and lyocell. The name comes from the large vats that hold the dye, and is one of the ancient forms of dyeing; this method was often used to dye materials indigo. Vat dyes are used for fabrics that require a solid, even shade of colour or one colour but using a resist dye technique such as tie-dyeing.
You may also like: Mechanism, Application Methods and Uses of Vat Dyes
Comparison between Reactive Dye and Azoic Dye:
- Limited shade range in Azoics.
- Dyeing method is very complex with too many variables in naphtholation, diazotisation and developing baths.
- Color fastness to Chlorine is better in naphthols.
- Rubbing and Light fastness are inferior in azoics.
- Dark and bright reds, maroons and ornages can be produced in azoics which are difficult in reactives.
- Azoics are suitable for Tie-dye and space dyeing.
Comparison between Vat Dye and Azoic Dye:
- Azoics are economical than Vat dyes.
- Bright reds, oranges and deep maroon shades are possible in Azoics.
- Limited Shade range in Azoics.
- Bright pinks, bright Blue, olive green, green and blacks are not possible in Naphthols.
- No fear of photodegradation in Naphthols.
- Rubbing na dlight fastness is inferior in Naphthol dyeing.
- More Suitable for Tie-dye and space dyeing.
You may also like:
- Color and Textile Dyes – An Overview
- Synthetic Dyes Used in Textile Industry
- Environmentally Friendly Dyes for Fabrics
- Natural Dyes: Properties, Classification, Production, Advantages and Disadvantages
Founder & Editor of Textile Learner. He is a Textile Consultant, Blogger & Entrepreneur. Mr. Kiron is working as a textile consultant in several local and international companies. He is also a contributor of Wikipedia.
I need vat dyes and vat dispers dye difference ?pls sends email