Printing on silk in direct style
Acid dyes are most suitable for printing of silk. The typical composition is as follows:
|Acid dye||x parts (depending on the depth of shade)|
|Hot water||100-150 parts|
|Glycerine or urea||25-50 parts|
|Ammonium oxalate or ammonium sulphate||20 parts|
|Wetting agent||10-20 parts|
|Thickener (Guar gum or Gum Indalca paste)||balance parts|
Pigment color printing though suitable for cotton is not suitable for printing of silk. This is due the fact that commercial binders available in the market are designed for cotton printing.
Discharge printing of silk
In Rajasthan discharge printing of silk is quite common. While discharge printing of silk following precautions must be taken-
- Proper selection of dye for dyeing before discharge printing is essential. Make sure the dye used for dyeing is dischargeable.
- White discharge paste should be neutral or slightly acidic to avoid the degradation of silk during steaming.
- When vat dye is used for color discharge effect, the print paste used is alkaline. Quantity of alkali should be taken according to the experience. Otherwise there is danger of silk degradation during steaming resulting is strength loss or many times the tearing of silk at the printed portion.
- From the point of view of preserving the strength of silk, non-dischargeable acid or basic dyes are recommended for color discharge. Since the discharge paste has mild acidic pH which is not harmful to silk and thus silk degradation can be prevented.
- Steaming is the most critical operation during discharge printing. The whole success of the discharge printing depends on the uniform steaming of the fabric. The present practice of steaming of generating steam by heating water underneath the container in which the fabric in the form of layers is steamed is not satisfactory and the reproducibility of results is not guaranteed.
- A star ager along with using the steam generated in a boiler is recommended for satisfactory results.