How to Evaluate Softener Performance? Master the Essence of Softener Performance Testing

As an essential auxiliary in textile finishing, the performance of softeners directly impacts the fabric’s feel, comfort, and durability. Therefore, accurate testing of softener performance is of paramount importance. Below are several commonly used methods for testing softener performance, aiming to help chemical engineers and textile professionals understand and master them.

1. Tactile Feel Evaluation

Tactile feel evaluation is the most intuitive and fundamental method for testing softener performance. Typically, experienced operators use direct touch to subjectively assess the fabric's softness, smoothness, and fullness. The advantage of this method is its simplicity and ability to directly reflect the fabric's tactile characteristics. However, it is somewhat subjective, as different operators might provide varying evaluations. Therefore, it is often combined with other objective testing methods for a more comprehensive assessment.

2. Heat Resistance and Yellowing Resistance Test

Heat resistance and yellowing resistance are crucial indicators for assessing the thermal properties of softeners. The test involves subjecting the softened fabric (colored fabric for heat resistance, bleached fabric for yellowing resistance) to baking (or ironing) at (185±2)℃ for 3 minutes, followed by cooling, and then observing and comparing the color difference or yellowing between heated and unheated fabric.

Testing Method: Heat treatment is performed using a hot air dryer, oven, or sublimation fastness tester. Then, the color is assessed using fading gray sample cards or grey scale cards for discoloration. The whiteness change before and after heating can also be measured to evaluate yellowing performance.

Note: Test conditions such as temperature and time should be adjusted depending on the fiber type, and these should be clearly stated in the report.

3. Elasticity Test

Elasticity is an important indicator for measuring fabric elasticity and recovery. The test involves cutting the sample into a specific size strip, marking the predetermined length under relaxed conditions, then applying different weights to measure the change in the distance between the markings, and calculating the elongation and recovery rate.

Test Method: Cut the sample into strips of 24 cm along the warp and 2 cm along the weft, marking 20 cm as the predetermined length. Clamp the top of the sample, apply a 5g load, and after 1 minute, measure the distance between the markings (L2). Then apply a 200g weight (while keeping the 5g load) and after 1 minute, measure the distance again (L3). Calculate elongation and recovery rates based on L1 (original length), L2, and L3.

Calculation Formula:

Elongation = (L2 - L1) / L1 × 100%;

Recovery = (L2 - L3) / (L2 - L1) × 100%.

Note: For knitted fabrics, a 100g load should be applied when measuring L2.

4. Fabric Abrasion Resistance Test

Abrasion resistance is one of the key indicators of fabric durability. The test uses a special abrasion tester to perform flat abrasion, fold abrasion, or bending tests until the sample is worn or torn, recording the number of friction cycles and calculating the average value.

Instrument and Materials: Three-in-one abrasion tester (e.g., Japanese import), disc-type fabric abrasion tester (for flat abrasion), abrasives, circular cutter, ruler, etc.

Test Method: Depending on the testing requirement, select flat abrasion, bending abrasion, or fold abrasion methods, and conduct the test under specified conditions such as friction speed, pressure block weight, and air pump pressure. Record the number of friction cycles and calculate the average.

Note: The block or pressure block weight used should be selected based on the fabric’s mass per square meter.

5. Softness Measurement - Heart-Shaped Ring Method

The heart-shaped ring method is an objective evaluation method for fabric softness. The test involves attaching the sample to a strip to form a heart-shaped ring structure, measuring the distance from the top of the strip to the lowest point of the heart-shaped ring (L). The larger the L value, the better the fabric's softness; otherwise, it is relatively poor.

Sample Preparation: Cut 2.5 cm × 25 cm samples in the warp and weft directions, 10 pieces for each.

Test Steps: Attach the samples to the strip to form the heart-shaped ring, then measure the L value. Measure five times each for the warp and weft directions and both the front and back of the fabric to get an average value.

Note: Softness can also be tested by measuring stiffness; these two tests are inversely related. The shorter the anti-bending length, the better the softness; otherwise, it is relatively poor.

6. Drapability Test

Drapability is the ability of fabric to form a beautiful contour and wrinkles when suspended, related to the fabric’s softness and weight distribution.

Sample Preparation: Take two round samples with a diameter of 24 cm and no wrinkles, making a hole of 0.4 cm diameter in the center of each sample. The test uses a specialized drapability tester.

Test Steps: Prepare a tracing paper the same size as the sample and accurately weigh its mass. Place the sample on the drapability tester and apply tracing paper, then gently press for 3 minutes. Measure the fabric’s projection after it drapes and cut out the traced pattern, weigh it again.

Calculation: The drapability coefficient, F, is calculated by:

F = (m3 - m2) / (m1 - m3) × 100%,

where m1 is the weight of the paper corresponding to the sample size, m2 is the weight of the paper corresponding to the holding disc size, and m3 is the weight of the paper corresponding to the draped projection size. The smaller the drapability coefficient, the softer the sample.

7. Needle Crack Fastness - Sewing Test

Needle crack fastness or sewing performance is the ability of fabric to resist needle piercing and breaking during the sewing process.

Test Machine: High-speed sewing machine with a speed of 4000r/min, needle sizes ranging from 9# to 14#, ensuring smooth, undamaged needle tips.

Test Method: The sample is conditioned for more than 24 hours. A rectangular fabric sample of 60 cm in the warp direction and 15 cm in the weft direction is folded into four layers and sewn in a grid pattern, with a stitch density of (11±1) stitches every 2.5 cm. After sewing, the sample is inspected under a magnifying glass, and the number of fibers broken by the needle is counted, then the percentage of broken needles is calculated.

Calculation:

Needle break rate = (Number of broken fibers) / (Total number of needles) × 100%.

Note: If no high-speed sewing machine is available, a home sewing machine can be used at maximum speed for the test. If no fiber breakage is observed, the sample can be soaked in a specific detergent solution and rubbed before re-inspecting.

8. Woven Fabric Anti-Slip Test

Anti-slip performance measures the ability of fabric yarns to resist slippage at the seam.

Test Instrument: Fabric strength tester with a stretching speed of (100±10) mm/min.

Sample Preparation: Take one sample from the warp and one from the weft direction (treated and untreated fabrics), each 35 cm × 10 cm. A 10 cm fold line is marked, and a straight seam is sewn 10 mm away from the fold.

Test Method: Clamp the sample on the fabric strength tester, apply a pre-tension of no more than 2N, then apply stretching load to measure the yarn slippage length.

Note: This simplified method omits the load-extension curve plotting and slippage calculation in GB/T 13772.1-1992.

9. Surface Friction Test

Surface friction measures fabric roughness and sliding resistance.

Test Equipment: Consists of two wooden boards, each with a test fabric affixed. One board is fixed while the other can be tilted.

Test Method: To ensure tight contact, place a weight on the upper board. Raise the lower board until the upper board starts to slide, measuring the angle θ. The static friction factor μ = tan(θ).

10. Fabric Style Test

Fabric style is a comprehensive reflection of fabric feel, appearance, and physical performance.

Test Principle: A fabric style tester decomposes the physical interaction of the hand with the fabric into basic mechanical forces such as tension, bending, compression, shear, and friction, and quantifies them using appropriate methods.

Test Method: The fabric style tester combines the measurement of individual mechanical properties into one instrument, enabling the objective, quantitative assessment of fabric hand feel. These individual properties have been described in previous methods, but the fabric style tester provides a more comprehensive evaluation.