Vat Printing

Experiment no.: 09 Experiment name: Printing of Cotton fabric with Vat Dyes. Introduction: Printing is the process by which a design is formed on the fabric surface by applying colorants with stencils, rollers, wooden blocks or screens. Normally fabrics are printed on one side of the fabric or both side of the fabric. In this process, the fabric is printed on the surface of the fabric and here the does not penetrate into the fabric. In this experiment we have used screen printing method. There are two styles of discharge printing. Such as, white style and colored style. Here the white style is used. used.

Objects: The objects of discharge printing of cotton dyed fabric are given below: To know about the printing process. To know about the printing procedure of cotton dyed fabric. To know about the recipe of producing the printing paste. To know about the method of producing the printing paste. To know about the mechanism of printing with print paste. To know the functions of various materials and reagents used in the printing process. fabric. ic. To produce various designs on the surface of the fabr

Printing recipe: The recipe of producing printing paste for Vat printing of cotton fabric is shown below: Vat Dye: 3Parts. 3Parts. Wetting Agent (Glycerin): 3Parts. 3Parts. Rongolite C/ Hydroze : 4Parts. 4Parts. Potassium Carbonate (K2CO3): 3Parts. 3Parts. Thickener (Starch): 70Parts. Water: 14Parts. 14Parts.

Preparation of Print Paste: The usual process for the preparation preparation of print paste for Vat printing of cotton fabric is shown below: 8gm Starch + 1000cc Water, (TemperatureൈTime: 10minutes). (Temperature Time: 1000Cൈ10minutes) 10minutes). 3gm Vat dyes + 2cc Wetting agent to make the dye paste. 4gms Rongolite C+ C+ Small amount of water to make the solution. solution. 3gm Potassium Carbonate (K2CO3) + Small amount of water to make the solution. solution. Add all the solutions to make the printing paste.

Apparatus: The apparatuses used for discharge printing of cotton dyed fabric are given below: Cotton fabric sample. Printing screen. Thermometer. Bicker. Dyeing bath. Scissor. Gas burner. Measuring cylinder. Glass rod. Spoon.

Functions of chemicals: The functions of the chemicals used in discharge printing of cotton dyed fabric are given below: Rongolite©/Hydroze: The function of Rongolite©/Hydroze is to extract the color from the dyed fabric according to the design. Starch: The function of starch is to make the print paste thick. Titanium dioxide (TiO2): Titanium dioxide (TiO2) is used to letting the paste fix on the surface of the fabric. Egg elbomin: Egg elbomin is used to produce white effect on the design of the printed area of the fabric.

Working Procedure: The working procedure procedure of discharge printing of cotton dyed fabric is given below: At first add 15gms of hydroze with some water in a bicker and stir it with glass rod to make a paste. Next add 20gms of titanium dioxide with some water in a bicker and stir it with glass rod to make a paste. Then take 8gms of starch and 100cc of water in a dyeing bath and heat the dyeing bath by gas burner. When the starch and water has mixed and produced a thick paste then turn off the burner. After that add all the pastes in a bicker and and then stir it to form a mixture of print paste. Then place the dyed cotton fabric under the designed printing screen and put the print paste over the printing screen. After that the printing paste is dragged over the screen with a wooden brush for producing producing the screen design on the surface of the fabric. Next the fabric is put into the oven dryer for drying. Finally the fabric was taken for after treatment.

After treatment: The after treatment of discharge printing of cotton dyed fabric is given below: Drying ↓ Steaming ↓ Soap wash ↓ Cold wash

Precaution: The precautions that should be taken during discharge printing of cotton dyed fabric are given below: We should use apron while printing the fabric for safety. All the apparatus should be used carefully. The gas burner should be handled carefully for avoiding accidents. The printing paste should be stirred carefully to avoid spilling of the pastes. The chemicals should be measured carefully according to recipe.

We should be careful during after treatment as the print can easily be faded.

Conclusion: The printing is a common process and a process which is widely used as it spends less dyeing ingredients and at the same time is capable of producing required designs.