11 Difference Between Reactive and Vat Dyes!

Reactive dye and vat dye aren’t of the same dye class, right? Of course, we all know about it. So, there’s some crucial difference between reactive and vat dyes. Before finding out the difference between reactive and vat dyes, let’s know the basics of these two dyes.

Let’s get started….

Reactive Dye

Reactive dye is an anionic dye that is soluble in water. It has a reactive group in it that reacts with the fiber and makes a covalent bond with it. Thus it becomes an integral part of the fiber. It is the youngest and most important dye class for cellulosic materials. For cellulosic materials, worldwide consumption of reactive dyes in the mid-1980s was about 10-12% whereas in Japan alone it represented about 40% of total dye consumption.

Now isn’t the question peeps through your mind that why this dye is so popular? The answer might be the properties of reactive dyes like high brilliancy at lower cost, a wide range of shades, ease of application and of course its reproducibility. 

Let’s talk about its fastness properties. The lightfastness of reactive dye is very good with a rating of 6. Their wash fastness is also very good as they form a strong covalent bond with the fibers. These bonds let them tightly attached to the substrate. They have moderate rubbing fastness.

Procion, Cibacron, Remazol are the most commonly used commercial reactive dyes.

Cellulose as well as protein both the fibers can be dyed with reactive dye. For fixation, it requires an alkaline condition. Reactive dyeing method can be explained in three steps: 

  • Exhaustion
  • Fixation
  • Washing off

In practice, you will find out reactive dyeing carried out in discontinuous or semi-continuous processes in factory. But it is so simple to dye with reactive dye at home. So, if you want to know how to use reactive dye for dyeing your favorite outfit then click here.

You will find out different reactive dyes like hot brand, medium brand, cold brand. Again, alkali controllable dyes, salt controllable dyes or temperature controllable dyes, DCT, MCT, Vinylsulphone dyes. Pretty confusing right?

So, if you wanna know about the detailed classification of reactive dye then click here

Vat Dye

Vat dye is a water insoluble anionic dye. For the application of vat dye, the vatting process is required. In this process, vat dye is reduced by sodium hydrosulfite. After the dyeing procedure, it is oxidized to convert to its mother form or you can say the original insoluble form.

So, dyeing with vat dye involves three steps:

  • Vatting, a reduction process carried out with sodium hydrosulphite and caustic soda
  • Dyeing, impregnation of substrate with the dissolved dye
  • Oxidation to convert the dye into its original pigment form.

This dyeing procedure is also carried out at alkaline medium like reactive dyeing. Vat dyes have excellent all round fastness properties that can’t be achieved by the other dye class. They are ideal for colored woven goods such as handkerchiefs, shirtings, and toweling.

This dye is easily reducible. So, when it undergoes washing at boil under alkaline conditions, it may show poor fastness properties. Otherwise, it has very excellent fastness properties.

11 Difference Between Reactive and Vat Dyes

TopicReactive dyeVat dye
MECHANISMCovalent Bond Formation.

Good Affinity for the Cellulosic Fibers.

Smaller Molecule Size.
Vatting Process:

 {Converting Water-Insoluble pigment into a Water-Soluble dye}.

Redox Reaction occurs

Reducing agent HYDROSE provides attraction for the fibers. Again the dye is converted into the insoluble form inside the fiber
SOLUBILITYEasily Soluble in Water.

Good Affinity for Water.

Polar Nature.
In-Soluble in Water.

Adding Reducing Agents to become Soluble.
CHARGEABILITYNegatively Charged.

Remove Negative  Charge by Adding Salts,

i.e. NaCl
Negatively Charged.

Alkali is Used for Removing Charge.
SUBSTANTIVITYGood Substantivity for the Fibers.

High Degree of Fixation Efficiency.

pH Range: 7 – 11
Substantivity is good for Cellulosic Fibers.

High Fixation because of Reducing Agents.

pH Range :  12 – 15
FASTNESS PROPERTIESWashing: Good   

Rubbing: Moderate

Lightening: Good

Chemical:  Stable

Perspiration: Good
Washing:  good

Lightening:  Good

Crocking: Poor

Chemicals: Average

Perspiration: Good
APPLIANCESThey are Applied to Cellulosic, Protein and Polyamide Fibers;

 i.e. Cotton, Wool.
They are Applied to Cellulosic and Protein Fibers; i.e. Viscose Rayon, Wool.
COLOUR RANGEWide Range of Colors.

Brighter Shades.

All Colors are Achievable.
Large Range of Colors.

Dark Shades Available.

Major Colors: Indigo, Green and Black.
ENVIRONMENT BEHAVIOURNon-Environmental Friendly.

Carcinogenic Dye.
Non-Environmental Friendly.

Cancer Causing Dye
COSTU.S: 0.5 – 1.8 $/Kg.  

Cheap
U.S: 9.9 – 13.98 $/Kg

Average
EASE OF PROCESSEasyDifficult
POPULARITYWidely used for dyeing garments i.e. Ladies wear, Men’s wear, Kid’s wearWidely used in dyeing jeans or denim

The Last Though

Both the dyes have excellent dyeing properties. But for ease of use, reactive dye achieved the most popular and used extensively in our country.

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