In the dyeing process of the yarn dyeing machine, the pretreatment of the yarn will directly affect the final dyeing quality. The dyeing of sulphur dyes is divided into light and mercerizing, and individual dyed yarns are also bleached. If the scouring is poor, the yarn effect is poor, or the concentration of mercerized alkali is different, and the bleaching yarn contains more chlorine, which will directly affect the dyeing quality.
Therefore, before the actual dyeing of the yarn dyeing machine, the necessary inspection of the white yarn is required, and the whiteness is uniform, and there is no yellow spot, black spot, alkali spot, rust spot, stain and chlorine. The white yarn after dewatering must be covered with a damp cloth to prevent the surface from air drying. For the white yarn that has been piled up for a long time, it must be washed once before dyeing, otherwise a partial white strip or a light strip will be produced after dyeing.
It should be noted that, considering the slow dyeing of sulphur dyes, it is recommended to use high temperature dyeing, which is beneficial to the dyeing machine dye granules continuously melting and thinning, quickly penetrate and diffuse into the inner layer of the fiber, and the fiber yarn can be made. It is puffed and heated to obtain a better leveling effect.http://textiledyeingmachines.com/