Influence Factors of Color Fastness To Rubbing

1、Unsolidified dyes cause the most rubbing-fastness issues.

This is true for rough or hairy fabrics like velvet. It’s also true for hard fabrics like linen, denim, and printed paint fabrics. Dry friction easily builds up dyes or paints on fabric. This grinding even fractures colored fibers. This forms colored particles that make rubbing-fastness worse. The colour fastness to dry rubbing is further reduced. Velvet and hairy fabrics can abrade. The velvet’s surface and the friction cloth’s surface touch at an angle, not parallel. This increases the friction of the rubbing head. It makes such fabrics lose color fastness.

2、Lightweight fabrics, usually made of synthetic fibers or silk, have a loose structure.

This structure impacts the surface of the sample. In dry friction, the fabric’s looseness causes some slippage. This slippage increases friction and efficiency. But, wet friction is different from that of cellulose fibers.

The fibers have very low hygroscopicity. They do not expand much in water. The water also acts as a lubricant. Due to this, the fabrics have better color fastness to wet rubbing than dry rubbing.

For some specific fabrics, the color fastness to wet rubbing is better than to dry rubbing. In this case, the chosen dye will impact color fastness to rubbing. It’s performance, dyeing conditions, and finishing conditions will too. But, they are less important. The fabric’s structure and surface and other physical factors matter more.

Most of the products in which this occurs are still dark colours, such as black, red and navy. For fabrics like corduroy, twill, and paint print, their wet-rub color-fastness is usually level 2 or lower. This is due to the dyestuffs used and the printing and dyeing process. It is not better than their color-fastness to dry rubbing.

3、The influence of the chemical structure of reactive dyes

We test cellulosic fabrics dyed with reactive dyes for wet rubbing color fastness.

There are two main factors that cause colour transfer:

(1) The dyes dissolve in water. They transfer to the rubbing fabric when rubbed. This makes the original color fade and the fabric stained.

(2) Some of the dyed fiber breaks during rubbing. It forms tiny colored particles. These particles transfer to the rubbing fabric, staining it.

Factors that may affect the colour fastness of reactive dyes to wet rubbing are:

The dyes have a structure and characteristics. The fabric’s nature matters. So does pre-treatment, fabric breakage, and surface finish.

The dyeing process affects soaping after dyeing. The colour-fixing treatment affects fabric dyed after dyeing. Post-finishing affects dyed fabric.

The study shows that some covalent bonds are stronger. Also, it shows some differences in the stability and adhesion of bonds. These bonds are formed by reactive dyes with different structures and cellulose fibers. But, there is no big difference in their effect on the color fastness to wet rubbing of dyed fabrics. When wet rubbing happens, the dye’s covalent bond with the fiber does not break. This bond forms between the dye and the fiber. It would produce floating color if it broke. The dye transferred is usually oversaturated and not bonded to the fiber. The dye adsorbed is held by van der Waals’ force. This is the so-called floating color.

4、Reactive dyes influence the dyeing degree and color fastness of fabric.

They also affect the wet friction and dyeing depth. The wet friction’s effect on color transfer and dyeing depth is nearly linear. Too much dye cannot mix with fiber. It can only stick to the fabric’s surface and make floating color. This color greatly harms the fabric’s wet rubbing fastness.

Cotton fibers need special treatment when wet. Without it, expansion and friction rise, and fiber strength falls. These problems cause breakage and shedding in colored fibers. They also make colors transfer. So, before dyeing cellulose fibers, do pretreat them. This can include mercerization, burnishing, cellulase finishing, boiling, bleaching, washing, and drying. These steps can improve the fabric’s finish and gross effect. They can reduce friction and floating color. This will improve the fabric’s wet-rubbing color fastness.

5、Softeners improve the color fastness of reactive dye printing.

They do this through soft finishing. Softener lubricates. It reduces friction. This prevents the dye from coming off. Softeners can also form color clumps with anionic dyes. Dyes do not easily come off. At the same time, the color makes the dye less soluble. This can improve wet rubbing fastness. However, the softener has a hydrophilic group. It does not help improve wet rubbing fastness. In production, we can close the water-soluble groups of dyes using colour-fixing agents. We can do this by controlling the pH of the fabric’s surface. We also remove floating color and make the fabrics smooth. This process improves the wet rubbing fastness of the fabrics. Proper pre-drying in the first section can avoid the “swimming shift” of dyestuff. Pay attention to factors like the alkali amount, steam time, and washing method. These factors affect the degree of dye breakdown. Adequate soaping affects the floating color of dyed products.

After dyeing the fabric, especially long and rolling dyeing, wash it enough. This removes floating color and unreacted and hydrolyzed dye. It stops color fastness from being affected. If you don’t do this, the color fastness will be poor. Also, the color will become atrophied and dark.