Tuesday, May 16, 2017

Different Types of Printing on Denim Fabric

Printing on Denim Fabric:
Denim is a strong, durable fabric, once upon a time denim was worn only as working wear. But now it is widely used as a fashion wear. The most common denim is indigo denim, in which the warp thread is dyed, while the weft thread is left white. But giving the most attractive looking to denim wear, different types of printing are done on denim fabric.
Printing on Denim Fabric
Fig: Printing on Denim Fabric
For dyeing denim with indigo dye, warp threads heavily covered by starch mixed with indigo or sulphur dye. For printing denim you can use pigment print to cover the dark color of denim. For making it clearer, pigment dye applied is on the surface of the fabric. It is on the starch mixed with indigo or sulfur dye but not on the cotton fiber.

Different Printing Techniques on Denim Fabric:

Reactive printing on denim:
Reactive print like reactive dye is usually of better crocking standards and more colorfast than pigment print. However, we should know reactive print can be stand chlorine bleach, but pigment print or pigment dye can. In the process of reactive print, you can use the same rotary or screen to print, but you need additional equipment to finish the dye steaming and washing. It is important to know, in reactive print as well as reactive dye, if the process is not done correctly with the right amount of color fixing agent, properly steamed and washed; there will still be problems of color fastness and crocking, or even staining. The proficiency of the printing mill plays a very important part in the quality.
Reactive print on denim
Fig: Reactive print on denim
In addition to better crocking standard and color fastness, reactive dye can penetrate better into the fabrics. If the fabric is corduroy, the problem of the dyes not penetrating into the bottom of the rib should be greatly reduced. However, we still should be aware of the following:
  1. For 21 or 16 wale corduroy, it is likely that the printing can reach the bottom of the rib.
  2. For 11, 8, 6 and 4 wale corduroy, it is likely that bottom of the rib will not be printed as the ribs are too thick and will prevent the roller from reaching the bottom of the rib. Unless the buyer clearly understands this and accepts it, we should not proceed to make such fabric.
Fabrics printed with reactive dye are completely soft as the steaming and washing process takes away most of the starch from the fabric. This is another advantage of reactive print.

Discharge printing on denim:
Other than the above common printing techniques there is a special printing techniques called “Discharge print”. The technique is used in a case like the following:

Discharge print on denim fabric
Fig: Discharge print on denim fabric
You need a printed fabric with dark color ground and medium color print. For example: the ground is 90% dark green color and the print is 10% in pink color. To print the fabric of such design you can think of the following methods:

1. Print the 90% area in pigment dark green, leaving 10% area not printed, for printed pink. Then print pink on the 10% area.

This method is okey, but the back of the fabric is white and the fabric is stiff because 90% of it is printed in dark color pigment dye.

2. Dye the fabric in dark green color and then print the 10% pink on it to cover the ground color, dark green. You can do that by mixing the pink dye with white power in order to be opaque to cover the ground.

This method is okey, but the pink design will be raised. You can feel it by hand. The pink print may crack from washing.

3. You can dye the fabric in pink and print 90% of dark green to cover it except the 10% area where you want the pink design to show.

This method is okey, but the pink color underneath the dark green color may distort the dark green color. Besides the fabric would be stiff because 90% of it is printed with dark color pigment dye.

Problem and solution:

As you can see, none of the above is satisfactory. In a case like this, if we use discharge print, we would solve all the problems:

This is how discharge print is done. First you dye the fabric in dark green (in reactive dye) so the fabric is solid dark green, front and back, and soft. Then you print the 10% area with bleach so that 10% area becomes white. Now you print pink on the 10% area.

Resist print on denim:
There is another printing method which is similar to discharge print but better in certain ways and cheaper. This is called “Resist Print”. Let us use the same example that we used in discharge print to explain.

You have a design with 10% area in pink color, and balance 90% in dark green.

To print the above described design, now you prepare the pink color pigment dye mixed with bleach. As explained previously, pigment dye can stand bleach of any kind, and so the bleach in the pigment dye would not do any harm to the pink color.

Resist Print on denim
Fig: Resist Print on denim
Now you start to print the fabric with the pink pigment dye on the 10% area, when the printing is done, you get the fabric through the heating system to make the pigment dye more securely adhere to the fiber the fabric and at the same time form a protective film on the surface where the pink color print is.

When the above is all done, you then print full coverage in reactive dye to cover the total area of fabric in dark green. After the printing is all finished you have process the fabric through steaming and washing. When washed, the dark green reactive dye which covers the design in pink color will go away making the pink design appear again.

This method is specially good if the design is drawn in such a way that precision in the registration of each color is needed. In resist print no overlapping or gap will take place.

You can also like:

  1. What is Discharge Printing? | Discharge Printing Methods
  2. Styles of Printing or Printing Styles
  3. 20 Key Differences between Dyeing and Printing
  4. Denim Manufacturing Process from Fiber to Finishing
  5. Different Types of Denim Fabric Used in Apparel Manufacturing