Printing of cotton fabrics with vat dyes:
When the cotton cloth is printed with the help of VAT dye, it is a very high-quality printing. Because the washing fastness, light fastness, and rubbing fastness of the fabric printed by this dye are very good. VAT dyes are marketed in different types and categories. However, VAT paste is specially made for printing by VAT dye. However, in conjunction with Turkish Red Oil, the powder class is used for dyeing and printing. Today we will learn how to print cotton fabric indirect style by VAT dye. https://bdfabric.com/cotton-printing-by-discharge-and-resist-style/
Table of Contents
Direct style printing:
In this method, the printing paste is applied directly to the cloth. Vat dye powder or paste thickener, solvent, water-soluble product, reduction chemical, catalyst, dispersing agent, alkali and reducing agent, etc. are mixed here to make printing paste. British gum is best here as a thickener. Apart from this, starch, gum tragacanth, etc. also work well. Cotton fabric printing by VAT dye can be done in two ways. E.g.
1. Potash rongalite method.
2. Potash caustic method.
Printing paste can be done in 2 ways in the mentioned 2 methods.
(A) Without pre-reduction
(B) With pre-reduction
1. Printing of cotton fabrics with vat dyes-Potash rongalite Method:
This method is widely used for the VAT dye printing process. Its application method is very simple and the desired result is obtained. In this method, VAT dye can be used without pre-reduction and with pre-reduction. The use of VAT dye paste in a method without pre-reduction is more acceptable. However, both paste and powder brands can be used in the pre-reduction method.
Without pre-reduction:
Recipe:
Vat dye (in the form of a paste) → 100 – 125 grams
Glycerin → 50 – 65 grams
Soluble salt B → 30 grams
Starch – Tregakanth paste → 400 grams
Potassium carbonate → 80 – 120 grams
Rongalite C → 60 – 100 grams
Water → 150 – 210 grams
Total → 1000 grams printing paste
With pre-reduction:
Recipe:
Vat dye (in the form of a paste) → 100 – 125 grams
Glycerin → 50-75 grams
Soluble salt B → 30 grams
Starch – Tregakanth paste → 500 grams
Potassium carbonate → 60-100 grams
Water → 150-200 grams
Sodium hydrosulfite → 40 grams
Rongalite C → 130 grams
Total → 1000 grams printing paste
Sodium hydrosulfite (hydrogen) acts as a vatting for dye.
2. Potash Caustic Method:
Most VAT dyes give very good results in this method of printing. This method is also used without pre-reduction and with the help of pre-reduction.
Printing of cotton fabrics-Without pre-reduction:
Recipe:
Vat dye (in the form of a paste)→ 80 grams
Alkaline thickener → 500 grams
Neutral starch (British gum paste)→ 140 grams
Water→ 120 grams
Rongalite C → 160 grams
Total → 1000 grams printing paste
Printing of cotton fabrics with vat dyes-With pre-reduction:
Recipe:
Vat dye (in the form of a paste) → 300 grams
Dried British gum → 100 grams
British gum paste (50%) → 230 grams
Glycerin → 20 grams
Urea→ 20 grams.
Potassium carbonate (90° Tw) → 100 grams
Sodium hydroxide (60° Tw) → 30 grams
Hydrosulfite → 40 grams
Rongalite C → 160 grams
Total → 1000 grams printing paste
Fabric printing is done by making paste in the above 4 methods. Then the cloth is well dried. However, high heat cannot be used. The Rongalite C is broken. As a result, there is no proper reducing during steaming.
Steaming:
After drying, the fabric is steamed at 100°C to 102°C for 5 minutes in a rapid ager machine as soon as possible.
Oxidation:
This oxidation is done after steaming to bring the molten VAT dyes back to insoluble VAT pigments.
