What causes uneven dyeing on the edges of fabric?

Uneven dyeing of fabric edges is a common dyeing problem that can be caused by a variety of factors. Here are some of the main reasons that may cause this problem:

1. Uneven distribution of dye liquor: During the dyeing process, if the dye liquor is unevenly distributed on the fabric, it may cause the dyeing effect of the edge and the center part to be different. This may be caused by problems with the dye liquor circulation system or design defects in the dyeing equipment.

2. Uneven fabric tension: During the dyeing process, if the fabric tension is uneven, it may cause the edge part to roll up or fold, which will affect the penetration and distribution of the dye liquor, resulting in uneven dyeing.

3. Edge effect: The edge part of the fabric is more exposed to the dye liquor than the center part, so it may absorb more dye, resulting in a darker color at the edge. In addition, the edge part may be subjected to more mechanical stress during the dyeing process, which will also affect the uniformity of dyeing.

4. Improper dyeing process parameters: Improper control of process parameters such as dyeing temperature, time, and pH value may also cause uneven dyeing. For example, if the dyeing temperature is too high or too low, the dyeing rate and diffusion performance of the dye may be affected, resulting in different dyeing effects at the edge and the center part.

5. Uneven fabric pretreatment: If the fabric pretreatment before dyeing (such as desizing, scouring, bleaching, mercerizing, etc.) is uneven, it may cause different hygroscopicity and dye affinity of different parts of the fabric, thus affecting the uniformity of dyeing.

6. Improper dye selection: Some dyes have poor diffusion and leveling properties, which can easily lead to uneven dyeing. Choosing suitable dyes and auxiliaries can effectively improve the uniformity of dyeing.

In order to prevent uneven dyeing of fabric edges, the following measures can be taken:

- Ensure uniform distribution of dye liquor, which can be achieved by improving dyeing equipment and dye liquor circulation system.
- Control the tension of the fabric to avoid curling or folding of the edge.
- Optimize the dyeing process parameters to ensure the stability of parameters such as temperature, time, pH value, etc. during the dyeing process.
- Strengthen the pretreatment of the fabric to ensure uniform hygroscopicity and dye affinity of various parts of the fabric.
- Select dyes and auxiliaries with good diffusion and leveling properties.

Through the above measures, the problem of uneven dyeing of fabric edges can be effectively reduced and the dyeing quality can be improved.