Dry and wet rubbing colour fastness of fabrics

Common standard for color fastness to rubbing

Chinese standard: GB/T 3920

International Standard: ISO 105 X12/X16

American Standard: AATCC 8/AATCC 116

Japanese Standard: JIS L0849 Type I /Type II

The color fastness of textiles to rubbing can be divided into dry rubbing fastness and wet rubbing fastness.

Color fastness to rubbing refers to the degree of color fading of dyed fabrics after rubbing, and is an assessment of the resistance of dyes to mechanical friction.

Factors affecting color fastness to rubbing:

a. Types of fabrics with poor color fastness to dry rubbing: rough or brushed surface, fluffed fabrics, hard fabrics such as linen, denim fabrics, pigment-printed fabrics, the dyes or other colored substances accumulated on the surface are ground down by dry rubbing, Or some colored fibers are broken to form colored particles, which reduces the degree of color fastness to dry rubbing; in addition, for sanded or raised fabrics, there is a certain angle between the fluff on the surface and the contact surface of the abrasive cloth, which is not parallel. The frictional resistance of the abrasive cloth increases, and the color fastness to dry abrasion also decreases.

b. Cellulosic fiber fabrics are generally dyed with reactive dyes. There are two reasons why the dyes on the test fabrics migrate to the abrasive cloth:

   ▲The water-soluble dyes are transferred to the abrasive cloth during wet rubbing. The reactive dyes and cellulose fibers are bound by covalent bonds. The type of this bond is very strong and will not be broken due to friction. Those dyes bound to cellulose fibers by van der Waals force (so-called floating color) will be transferred to the abrasive cloth under wet rubbing, resulting in poor wet rubbing fastness.

   ▲The dyed fibers are broken during the rubbing process, forming tiny colored fiber particles and transferring them to the abrasive cloth, resulting in poor color fastness to wet rubbing.

c. The color fastness to wet rubbing of reactive dyed fabrics has a lot to do with the depth of dyeing. When dyeing dark colors, the concentration of dyes used is higher, because excessive dyes cannot be combined with fibers and can only accumulate on the surface of fibers. It becomes a floating color, which seriously affects the color fastness of the fabric to wet abrasion. The degree of pretreatment of cellulose fiber fabric directly affects the color fastness to wet rubbing, mercerizing, singeing, scouring, bleaching and other pretreatments can make the fabric surface smooth, reduce friction resistance, and improve the color fastness to wet rubbing of the fabric.

d. For light and thin polyester fabrics, when dry rubbing, because the fabric is relatively loose, under the action of friction, the fabric will partially slip, which will increase the frictional resistance; but such fabrics are wet rubbing color. In the fastness test, because of the low water absorption of polyester, water plays a lubricating role during wet grinding, so in this case, the color fastness of the fabric to wet grinding is better than the color fastness to dry grinding. Some darker colors such as black, red or navy blue have a more pronounced effect. However, for corduroy fabrics, under wet conditions, due to the dyes and printing and dyeing processes used, the usual color fastness to wet rubbing is only about 2 grades, which is not better than the color fastness to dry rubbing.

e. The softener added in the finishing process plays a lubricating role, which can reduce the coefficient of friction and dye shedding. The cationic softener and anionic reactive dyes will react to form a lake, which reduces the solubility of the dye and improves the fabric. Wet rubbing fastness. Softeners with hydrophilic groups are not conducive to the improvement of wet rubbing fastness.