Dyeing factories generally make small samples in the laboratory, and then enlarge the sample production in the workshop according to the sample. The causes of inconsistent color light and color difference between the sample and the large sample may have the following aspects:

1 different fabrics

Prior to dyeing, the grey cloth should be subjected to scouring or degreasing, and the small sample may not be pretreated, or the small sample processing method may be different from the production of the large sample on the shop floor. The moisture content of the grey cloth is different, and the moisture content of the small sample has different effects, and different weighing scales are also different due to moisture content. For this purpose, the grey fabrics that are required to be sampled must be exactly the same as those produced on the shop floor.

2 different dyes

Although the dyes used for the demos and the dyes used for the large samples have the same type and strength, but the batch number or the sample size is not accurate enough, it may cause differences between the sample and the large sample. It is also possible that large quantities of dyes for production have become agglomerated and damp, and some of the dyes are not stable, resulting in a decrease in the amount of force.

3 different bath pH

Generally, it is more accurate to master the pH value of the dyeing bath in the sample, and the pH value of the sample is not stable or there is no acid-base buffer during production. Since the vapor is alkaline when dyeing, the pH value of the sample increases during the production. Some disperse dyes are The ester group, amido group, cyano group, etc. are hydrolyzed under alkaline conditions at high temperature. There are also some dyes whose carboxyl groups are ionized under alkaline conditions, with increased water solubility and lower dye uptake. Most of the disperse dyes have a normal, stable, and high dye uptake at pH 5.5-6. However, when the pH rises, the shade changes. Such as dispersed and black S-2BL, disperse dark blue HGL, disperse gray M and other dyes at pH> 7 or more, the color light changes significantly. In some cases, the grey cloth is not fully washed after the pre-treatment and is alkaline, and the pH value of the dyeing bath is increased when dyeing, which affects the shade.

In addition, is the pre-treatment of grey cloth pre-shaped?

If the gauze fabric has been pre-shaped, the gauze fabric has not been pre-shaped, and even the large sample and the small sample have been pre-determined, and the setting temperature is different, which can also result in different colors.

4 bath ratio effect

For the sample test, the bath ratio is generally larger (1:25-40), and the sample bath ratio varies depending on the device, generally 1:8-15. Some baths of disperse dyes have less dependence than others, and some have a large dependency, which causes color differences due to the difference between the sample size and the large sample bath ratio.

5 post-processing effects

Post-processing is one of the reasons that affect the color difference. Especially in medium and dark colors, in addition to the presence of a floating color, it is also possible to influence the color shade and produce a certain color difference if the reduction cleaning is not performed. Therefore, the reduction must be consistent with the sample.

6 Effect 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 matching. In case of high-temperature and low-temperature color matching, the setting temperature should not be too high in the heat setting to avoid excessive temperature, causing some dyes to sublimate and affect the color light, resulting in color. The sample and large sample shape requirements are basically the same. Because the shape of the pre-treatment or not, the setting conditions (temperature) have a great influence on the color-receiving properties of the polyester (the greater the degree of setting, the lower the dyeing property). Therefore, the sample cloth must be the same as the large sample (that is, before production It is anxious to use the workshop semi-finished products.)

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