Why Is There Always A Color Difference Between Lab Dip Samples And Bulk Samples?

- Jun 01, 2020-

Dyeing factories usually make lab dips in the laboratory, and then enlarge the samples in the workshop according to the lab dips. The reasons for the inconsistent color and color difference between the lab dips and the bulk samples may be as follows:


1. Different grey cloths

Before dyeing, the grey fabric should be refined or degreased, and the lab dip may not be pre-treated, or the sample processing method is different from the bulk sample production in the workshop. The moisture content of the grey cloth is different, and the influence of the moisture content of the sample is greater. Because the moisture content is different, the weighing is also different. For this purpose, it is required that the grey fabric to be sampled must be exactly the same as the grey fabric produced in the workshop.


2. Different dyes

Although the dyes used in lab dips and the dyes used in bulk samples have the same varieties and force points, different batch numbers or inaccurate weighing of lab dips may cause differences between lab dips and bulk samples. It is also possible that large-scale production dyes have agglomerated and become wet, and some dyes are unstable, causing a drop in force.


3. Influence of liquor ratio

In the lab dip test, the liquor ratio is generally large (1: 25-40), and the bulk sample liquor ratio varies according to the equipment, generally 1: 8-15. Some liquor of disperse dyes are less dependent than others, and some are more dependent, so that the color difference is caused by the different sample and bulk sample liquor ratios.


4. Impact of post-processing

Post-processing is one of the reasons that affect the color difference. Especially for medium and dark colors, if there is no reduction cleaning, in addition to the existence of floating colors, it can also affect the color light and produce a certain color difference. Therefore, the reduction and cleaning must be consistent with the lab dip and the bulk sample.


5. The influence of heat setting

Disperse dyes can be divided into high temperature type, medium temperature type and low temperature type. The same type of dye should be selected for color mixing. In case of high-temperature and low-temperature color mixing, the setting temperature should not be too high during heat setting to avoid the temperature being too high, causing some dyes to sublimate and affect the color light, resulting in color difference. The setting conditions for the lab dip and the bulk sample are basically the same. Because the pre-treatment setting or not, the setting conditions (temperature) have a great influence on the color absorption of polyester (the greater the setting, the lower the dyeability), so the cloth for lab dips must be consistent with the bulk samples (that is, before production) Reproduce with the semi-finished products in the workshop), which is one of anxiety.