Dyeing causes physical and chemical changes in the fabric, reflecting light on the fabric and making it look radiant. At the present time dyeing and printing on textiles is a very important issue. In ancient times, silk was printed with natural colors. But with the development of modern technology, there is a huge change in dyeing and printing. At present the effectiveness of silk fabric printing through acid dyeing is very attractive.
What is acid dye?
Acid dyes are made up of a number of acids or chemical salts of acids. This type of dye is called acid dye because different acids are used when dyeing yarn or cloth. Acid dye has complete chromatogram and bright color properties.
Chemically acid dyes are subdivided into different types such as nitro, nitroso, monoazo, diazo, xanthane, azine, quinoline, anthraquinone etc. They are water soluble and addicted to wool, silk and nylon fibers. They are applied to the fiber by neutral or acid dye containers.
Silk dyeing by acid dyes:
Direct use of acid dye is dangerous in case of cellulose fibers. This is because the presence of acid can have a detrimental effect on the color of cellulose. Acid dyes are mainly suitable for nylon, silk and various animal fibers. The effectiveness of acid dyes on silk animal fiber is very good; the color is more mature and brighter than field special fur.
Pre-treatment of silk fabric before printing:
Silk consists of two single filaments, the main body of which is sericin, and the outer layer is covered with sericin. Most pigments, oils, waxes and inorganic salts are present in sericin. These impurities have a large effect on the effect of printing and dyeing, so they must be removed before dyeing. Removing sericin from silk is called silk degumming. Gray-silk fabric is stiffer, less glossy and less white due to the presence of sericin. Therefore, before printing silk fabric, pre-treatment is done with the following material:
- Soap… … … … … … … … …> 0.5 to 2.0 G/L
- Sequestarent… … … … … > 0.5 to 1.0 G/L
- Sodium bi- carbonate … > 0.5 to 2.0 G/L
- Temperature … … … … > 50 to 70°C
- Time … … … … … … …> 20 to 25 minute
Printing of silk fabric with acid dyes:
The color of normal silk is off-white. When real silk is needed, the fabric is bleached with hydrogen peroxide as a bleaching ingredient. The following ingredients are used to make the paste of silk fabric printing.
- Acid dye……………………> 40 gram
- Boiling water…………….> 335 gram
- Glycerin……………………> 25 gram
- Gum tragacanth…………> 550 gram
- Tartaric Acid………………> 50 gram
………..Total = 1000 gram
The pre-treated silk fabric is printed with the above paste.
The silk printing method is almost like wool. In this process one has to make soft soap liquor. To make this solution, 25% ordinary soap liqueur or boiled soap liquor (boiled – off – liquor) has to be mixed with 75% water. In the first case, the soapy water obtained by boiling the silk with soap is called soap liquor. In the case of silk, this mild soap solution has to be mixed with acetic acid instead of sulfuric acid. The temperature of the mixture is first slowly raised to 40°C. Now have to add the solution of the selected acid color little by little. The cloth can then be immersed in a dye bath and the temperature can be gradually increased to a maximum of 85°C. However, it is better to keep control within 80°C. The silk fabric is then dried and steamed for 60 minutes under cottage steam and atmospheric pressure. It is then thoroughly washed in cold water. When all is dried at the end it is ironed.
- Acetic Acid: 4%
- Soft soap liquor: 25%
- Water: 30%
- Temperature: 80°- 85°C
- Time: 30 minute to 1 hour
The durability of the printing silk is enhanced by first treating it with 4% tannic acid and 1% amniotic tartar. The product can be processed in a solution of 4% acetic acid to increase the brightness. And when processed in a solution of turkey oil (T.R. oil), the smoothness of that silk cloth is increased many times. The acid dye method is used for commercial dyeing. In the textile industry, this color is called commercial color.
The process printing of silk fabric with acid dyes plays an important role in the textile industry. This is because it increases the brightness of the silk many times and the fabric is much smoother. As a result, the value of silk cloth in the market has increased a thousand times. Although silk dyeing and printing was done naturally in ancient times, now silk printing by acid dye is a popular process. Because naturally dyeing and printing is difficult and time consuming which is not applicable to silk printing by acid dyeing.
- Garments Merchandising By – Prof M A Kashem
- Textile Chemistry By – Dr. Md. Ali Nesar khan
Author of this Article:
B.Sc. in Clothing and Textile
Govt. College of Applied Human Science, Dhaka
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Founder & Editor of Textile Learner. He is a Textile Consultant, Blogger & Entrepreneur. He is working as a textile consultant in several local and international companies. He is also a contributor of Wikipedia.