Printing plays a special role in value addition of silk for both apparel and finished products. In the local market, printed silk has a higher share than many other natural and synthetic fibers. Majority of the silk fabric processed in India is printed in cottage sector by traditional method such as screen printing following either direct or discharge style. The printers who had been earlier using direct and basic dyes, have now taken to acid metal-complex and recently to reactive dyes.
During printing although the dye and the other ingredients of the print paste start getting dried up, some transfer of the dye inadvertently takes place from the reservoir paste to the fabric. But majority of the dye transfer takes place during the fixation stage, i.e., in steaming. After fixation, fixed dyes, unfixed dye and some adjutants will be present on the fabric, while unfixed/non-transferred dye, thickening agents and decomposition products of adjutants will remain on the fabric in printing paste phase.
Since textile printing in India is carried out largely in the cottage sector, even little dye stuff left on the fabric after post-printing process is undesirable, more so in case of precious silk. The authors present the details of a study conducted on the different washing practices prevailing in the industry and their merits.
While the unfixed dye results in poor fastness, the thickening agent and some of the adjutant could yield unpleasant features that remain on the fabric. It is, therefore, necessary to wash the unfixed dye and other adjutants of print paste.
Normally, printers in the cottage sector, wash
their silk printed goods according to their processing conditions.
Investigations have been conducted on pre- and post-printing operations pertaining
to silk. However, no systematic effort has been made to study the different
washing operations adopted for washing off these materials from the printed
In the present study, the efficacy of different washing cycles followed in commercial printing units has been investigated.
A plain woven soft silk fabric (39 g/ m2) was used for the study. The fabric was degummed and bleached in a single bath using the following recipe:
The degummed and bleached fabric was washed thoroughly in soft water and dried.