PRETREATMENT INFLUENCES REPRODUCIBILITY

Many dyeing plants don't pay attention to pre-treatment. Actually, many problems in dyeing processing because of ingnoring do enough pre-treatment. Impurity removal degree, whiteness, pH value after washing, purification of hydrogen peroxide after bleaching, amount of alkali carried by mercerized yarn, different tension affect gloss. When dyeing bobbin yarn, pre-treatment, dyeing and post-treatment are carried out in the same high pressure bobbin dyeing machine, and the pre-treatment effect is also different.

Generally, the dyeing factory pays more attention to force determination and weighing of dyes，but less attention is paid to the force determination and weighing of other chemicals. 

Caustic soda, soda ash, hydrogen peroxide is not analyzed, only calculated according to instructions, dye liquor are rarely titrated. So pre-treatment effect is different, causes difference of color depth and hue.

As mentioned, paying attention to compatibility, compatibility, sensitivity and quality of dyestuff, in order to ensure reproducibility.

RATIONALITY OF DYEING TECHNOLOGY INFLUENCES REPRODUCIBILITY

Although selecting appropriate dye, the dyeing process is designed not reasonable, there also be cylinder differences.  Such as temperature design, heating rate, holding time, amount of additives and feeding method scientificity, the rationality of post-treatment process design will affect the dyeing amount of dyestuff resulting in color difference.

Such as adding reactive dye solid alkali, fixation and hydrolysis of reactive dyes have a lot to do with the pH value of dye bath, the scientific feeding method is to maintain the Pu value at a fixed value (such as pH value is 11.5), which is related to the feeding method and feeding rate, if one-time feeding or feeding fast and slow all will cause pH fluctuations, amount of fixation and hydrolyzed dyes is different, finally eflects the different shades of light.