The purpose of fabric pre-treatment is to remove the slurry and fiber contained in the fabric waxy substances, pectin substances, polysaccharides, organic acids, nitrogen-containing substances, ash and other impurities to obtain good water absorption and a certain whiteness, which is beneficial to dyeing and finishing.
The importance of testing the gross effect
The level of wool efficiency is one of the important indicators to evaluate the scouring effect of semi-finished products and whether they can be dyed or printed. The quality requirements of cotton fabric after scouring are measured by the capillary effect. In continuous dyeing or printing, the padding dye solution (or printing paste) on the fabric only takes a few seconds to complete the dyeing (or printing process).
Countries have developed different methods for testing gross efficacy. Most factories use the capillary effect method, which means that the distilled water on the fabric rises to a height within 30 minutes, which should generally reach more than 8cm.
Some old factory workers have also concluded in practice that the instantaneous penetration of dripping water means that good penetration means that the wool effect is good and can be dyed or printed. Europe generally uses an improved rapid gross effect test method, which is the time required for distilled water to rise to a height of 1cm. The United States uses the AATCC rapid wool effect test method, that is, drip 0.5mL of water within 10 seconds, and observe the warp and weft diffusion width of the cloth surface in 30 seconds.
Method for testing capillary effect
1. Capillary effect testing method
First correct the horizontal position of the capillary effect tester and adjust the scale so that the zero point of the scale is aligned with the water tank surface. Then take the sample and cut it into two strips of cloth of 30cm in the warp direction and 5cm in the weft direction. Attach a 2-3g weight to one end and clamp the other end to the iron clip of the instrument. Let the cloth droop naturally into the water and record the time. After 30 minutes, observe the height of the cloth wetted by water. If there is unevenness, read the lowest value and use the average of the two cloth samples as the inspection data.
The capillary effect of fabric, unless the test conditions are specifically indicated, refers to the height H (cm) reached by distilled water rising along the warp direction of the fabric for 30 minutes at room temperature. (Figure 1)
Figure 1 Domestic habit testing method
2. Improved gross effect test method
Take the weft direction Test a cloth strip 2cm wide and 10cm longitude according to the above test method. Record the time it takes for distilled water to rise to a height of 1cm. If there are any unevenness, take the lowest value. (Figure 2)
Figure 2 Improved Gross Effect Test Method
3. Determination of rapid gross efficacy value
The rapid gross efficacy value is determined by the AATCC method. The dropper drips water at a height of 10cm onto the cloth stretched with a stainless steel stretcher. It takes 10 seconds to drip 0.5mL. Observe the spread width of the cloth in the longitude and weft directions in 30 seconds. You can first draw a line with a ballpoint pen and then measure the size. 4cm is pass, 5cm is good, and 6cm is excellent. When measuring, take the lowest value in the longitude and latitude directions. (Figure 3)
Figure 3 AATCC test method
4. Comparison table of different test methods for gross effect
Notes
1. In the above test methods, if the additives on the fabric are not removed cleanly, the accuracy of the test results will often be reduced. The surfactant on the test sample will often cause the wool effect to be falsely high. .
2. The results of the above test methods cannot accurately reflect the consistency of the entire wool effect of the fabric, but this deficiency can be made up by increasing testing points, or by using the national standard testing method. To test the difference in the overall gross effect of the semi-finished product.
3. In the American standard detection method, since the amount of distilled water added is fixed (0.5mL), the detection results of heavy fabrics will be relatively low.
4. The European standard detection method can reduce detection errors caused by operational factors by improving the test container.
5. In actual production, it is recommended to use the national standard test method to detect the entire wool effect of semi-finished products before pre-treatment, and use the American standard test method before dyeing. Test the instantaneous hair effect of semi-finished products.
</p
