Textile Printing Basics
Printing is defined as production of patterns or designed on the textile material other than the woven, painted or embroidered designs. It is referred as ‘Localized dyeing’ which simply means that dyeing is restricted to a particular part of the fabric that is desired by the designer. In printing the color is applied in the form of a thick paste which consist of dye in a concentrated form unlike in dyeing.
Stages involve in printing
- Preparation of the fabric;
- Preparation of the printing paste,
- Making an impression onto the fabric,
- Fixation pf the dried prints
- After-treatment
Let us understand the above mention stages in detail:
Preparation of cloth:
When a grey cloth from the loom
it contains various impurities. Natural impurities like waxes and fats on
cotton cloth makes it less water repellent. Presence of such unwanted material
on the fabric makes the fabric unsuitable for printing. Hence it is important
to prepare the fabric before printing to obtain the desired results. For
preparing the fabric for printing, the tiny fibers called as protruding fibers
have to be removed by the process of singeing, the size should be removed by
desizing and finally the fabric has to be scoured and bleached.
Preparation of printing paste:
The significant ingredients that
are used in the printing paste is the thickener and coloring matter. Besides
these two major ingredients many other ingredients are added. Addition
ingredients include pigment, reducing agents, wetting agents, oxidizing agents,
solvents, hygroscopic agents, catalyst, defoamers, acids and alkalis, carriers
etc.
Methods of printing:
Different types of equipment are used for producing different type of printed effect. The methods include:
- Transfer printing
- Roller printing
- Rotary screen printing by hand
- Block printing
- Screen printing
- Stencil printing
Fixation of the dried prints:
This process is also termed as steaming. Once the cloth is printed and dried, the dye is not technically carried onto the cloth, only a dried fine film which is made up of starch or gum thickener is placed on the top of the cloth. To shift the dye from the film into the cloth, steaming is carried out. Suring steaming the cloth is revealed to the steam which is around 100 degrees. Steaming can be either carried out batchwise are continuously.
After-treatments:
The steamed cloth contains
exhausted thickener film and others chemicals along with it. If the thickener
works to a temporary type it should be washed out from the steamed cloth. But
it has to be made sure that this is carried out without affecting the dye which
is so far transferred to the fabric.
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