New clothes and bags,
tend to be the lady’s favorite.
But a bag which you like,
can’t be taken out.
The reason for the problem，
comes from a cloth.
What’s going on?
A lady bought a cloth, after washing it not only pant were dyed, but the bag was dyed. More than $3000 bag was destroyed like this.
What exactly are the reasons for this？
In daily life, between clothes and bags, between clothes and clothes, between clothes and seats, between clothes and human skin. There are all kinds of rubbing, if the color fastness to crocking of textiles is not up to the standard, it will cause color loss, affect beauty, even will damage the skin, endanger health. For example, in the event of the bag being stained above, in the process of rubbing between the new clothes and the pants or bags, the dye color on the clothes rubbed against the pants and bags, causing the beloved designer bag to be disfigured, and the culprit is that the crocking colorfastness of the newly bought clothes is not up to standard. So what is the color fastness to crocking? How to test the rubbing color fastness of all kinds of textiles (especially clothes)?
Definition of Crocking Color Fastness
Crocking Color fastness is one of the tests for color fastness of textile and it’s also the most common test for textile in the course of trade. It refers to color shading degree of dyed fabrics and it can be divided into dry friction and wet friction.
Crocking fastness takes the staining degree of white fabric as grading principle, 5 grades in total. The higher the value, the better the crocking fastness.
The Test of Color Fastness to Crocking
Common standards for Crocking color fastness are: GB/T 3920-2008、ISO 105 X12:2016、AATCC 8 -2016. Their differences are as follows:
Take AATCC 8 as an example. Let’s take a look at the procedure:
Why is the friction resistance of the test not up to standard?
Influencing factor of Crocking Color fastness
1 Influence of friction resistance
(1)When the fabric surface is rough, sanded and raising, the friction resistance of the fabric surface increases and the dry friction resistance of the fabric measured is poor.
(2) When the fabric structure is loose and dry friction occurs, the sample will slip with the motion of the friction head, which makes the friction resistance increase.
(3) When conducting wet friction tests:
For Chemical Fibers (all are water-repellent), the moisture content on the cotton friction cloth will act as a wetting agent, reducing the friction resistance of the fabric surface, and the wet friction resistance of the fabric measured will be better than the dry friction resistance.
For the natural fibers (most of them are hydrophilic fibers), the water content in the cotton friction cloth will cause the hydrophilic fibers to absorb water and expand, and increase the friction resistance of the fabric surface.
2 The effect of surface float on a fabric (usually seen on a dark colored fabric)
(1) Because the concentration of dyes used in deep dyeing is higher than the saturation value, the excess dyes can not combine with the fibers and accumulate on the surface of the fabric to form floating color, which affects the wet crocking color fastness.
(2) After dyeing polyester fiber with disperse dyes and setting at high temperature, the dye moves to the surface of the fabric to form floating color, which makes the wet crocking fastness of the fabric decrease.
3 The influence of reactive dyes
(1) The water-soluble dyes are easily transferred to the friction fabric during wet friction, which causes the original color to fade and the friction fabric to stain
(2) The partially dyed fiber breaks during friction, forming tiny colored particles that are transferred to the frictional fabric, resulting in staining.
So, how to improve friction fastness?
Method of improving friction fastness
1 Proper pretreatment before dyeing, such as mercerizing, singeing, cellulase finishing, scouring, bleaching, washing, and drying, can improve the surface smoothness and wool effect of the fabric Reducing the friction resistance and improving the ability of the fiber to absorb dyes.
2 In the textile after-treatment, the fabric for full soaping, washing the fabric surface floating color.
3 For the high temperature setting of polyester fiber after dyeing with disperse dyes will cause the dye to move to the surface of the fiber and cause the decline of the color fastness to rubbing, the color fastness to rubbing can be improved to a certain extent by adding the fixing agent or the smoothing agent.
The problem of color fastness to crocking seems simple, but the factors involved are quite complicated. Whether from the control of the manufacturing process or the process of color fastness test evaluation, there are still a lot of problems. Welcome to the TESTEX Blog message and exchange the discussion together.