I. The choose of dye
There is a great variety of reactive dye with different quality level. So the choose of qualified dye becomes important.
1. The choose of bi-functional reactive dyes and multi-functional reactive dyes.
S-triazine reactive dye reacts with fiber and produces ester bond, whose acid-resisting ability is bad. Vinyl sulfones dye react with fiber and produce ether bond, whose alkalic performance is bad. So we choose bi=functional reactive dyes, whose acid-resistance and alkali-resistance ability is good.
2. Choose the dye with proper substantivity
If the substantivity of reactive dye is too high, it diffusion ability is bad. The dye will gather on the fabric surface and not extend to the inner of the fiber. The unfixed dye is more than expected and difficult to wash. If the substantivity is too low, if will influence the degree of fixation. So the substantivity should be medium. And we can refer to the manufactures data to choose.
3. Choose high fixation rate dye
The high fixation rate dye has little-unfixed dye. If the fixation rate is large than 80%, the undyed dye is few, and it is easy to remove the unfixed dye. If the fixation rate is less than 70%, (dye up-takings rate-fixation rate )is large than 15%. And its unfixed dye is hard to remove. And it is not suitable for dyeing medium and deeper color fabrics
4. Choose good up-taking dye
In the dyeing process, the dye consuming quantity should no more than 10% of the dyeing saturation value in general. The excessive dye can not be dyed completely. If the dye-fixing is not complete, unfixed dye will stain on the surface of the dyed fabric and influence the fabric’s fastness to wet rubbing. If we dye the deeper color fabric, we need to choose high absorbing rate, high fastness rate and high up-taking dye, such as bi-functional and multi-functional reactive dye.
II. Choose even count, smooth cloth, and treat with the high efficient preliminary treatment agent.
III. In the dyeing process, we should choose soft water or deionized water. They possess few ions like calcium ion, plasma ion which will influence the dyeing.
IV. The choose of dye fixing agents
High efficient dye-fixing agent is the agent that will combine with the fiber and produce compounds. When it reacts with the dye, it will crosslink with fiber at the same time, fixing the dye on the fiber and preventing it from drop, then reducing the fastness. The dye-fixing agent will combine the cationic groups of fiber and ironic ion of dye, producing saline. Thus, it functions as fixation.
V. The special auxiliary will help to decrease the consuming quantity of the dye and get the deep color effect. And the fastness to wet fastness will be improved.
In the process f dyeing deep color fabric, the using of alkali is high. We should pay attention to the process of water washing, soap washing and the alkali neutralization process. If there are alkali existing on the fabric, the dye will hydrolyze, the fastness to wet rubbing will decrease. Usually, the Ph value on the surface should be among 6.5-7.5. Larger than 9 or smaller than 3 is not allowed.
VII. Improve the cloth property after dyeing
Using bio-enzyme to finishing the fabric, the smooth of the fabric will increase, and the fastness to wet rubbing will increase at the same time.
VIII. The unfixed agent is not easy to be removed after reactive dye dyeing. After soap washing, the stripping agent can be adopted to strip the unfixed color and improve the fastness to wet rubbing.