The ability of fabric to resist water penetration under control pressure is basically measured by the water resistance test. The major standard used for this testing is AATCC 35. It includes measuring water penetration after exposing the fabric to rain. After this, the increase in fabric weight will be measured to determine the fabric’s actual performance under real-world conditions.
Importance of AATCC 35 Rain Test Over Basic Water Resistance Test?
AATCC 35 Water Resistance Test in the Laboratory
Cut a 2×2 cm sample and place it on a weighted blotter. After this, water will be sprayed onto the fabric surface for 5 minutes at 27 °C. The nozzle is set to 305mm to ensure uniform energy distribution.
A small variation in water spray or pressure can lead to a change in the end results of more than 10%. Usually, laboratories are not able to maintain the same water pressure throughout testing, which can affect the results. Additionally, sample conditioning at 65% RH and 21°C is essential to minimize fluctuations in the results.
Method to Interpret the Results
The results of the AATCC 35 test method are measured by evaluating the weight gain in the blotter, which indicates water penetration. If we get the result above 5 g, it will indicate the water Penetration due to failure of the fabric structure.
In real world conditions, products having results 1 g can perform well in light rain conditions. Products with 1-3 g results show moderate resistance.
During the interpretation of results, the fabric’s structure and finishes are also considered. Because, woven or knitted fabrics perform differently. The highly effective laboratories use water penetration data to measure the fabric’s actual performance under real-world conditions and design the fabric accordingly.
Testing Methods of AATCC 35 Method for Accurate Fabric Performance
Testing Principles and Measurement Methods
The AATCC 35 method includes spraying rainwater onto the fabric surface mounted on an already-weighed blotter. We will measure the weight gain on the blotter, from which we can determine the fabric’s water penetration.
The tight weave fabrics can increase water penetration, while water-repellent finishes like DWR can also prevent water but may fail with prolonged exposure to rain. A small variation in yarn density or surface coating can change the results by up to 1-2 g, which can hide the real fabric performance.
Effect of Pressure Variation During Testing
The main edge of the AATCC 35 test is that we can adjust the pressure head from 0.6 to 2.4 m. This helps us simulate different rain intensities for testing. Most labs conduct tests only at a single pressure, so they fail to measure fabric performance across different rain intensities.
As pressure increases, fabric failure will occur when weight gain exceeds 5 g. The modern labs plot a graph of pressure versus penetration to determine the fabric durability limits. For example, the fabric result is 1 g at 0.6 m pressure, increasing to 5 g at 1.5 m pressure.
This analysis of fabric under different pressures will help us measure the actual rain-resistance profile under real-world conditions.
Traditional Rain Testers and Their Limitations in Modern Laboratories
Common Errors in Testing and Variations
Traditional rain-test equipment relies heavily on the water column to control water pressure. This can produce variation in pressure heads due to manual control of the water column.
A small variation in the water column can change the intensity of rainwater, leading to changes in water penetration results by several grams. Other manual adjustments, such as a 305 mm nozzle distance, an improperly mounted sample, etc., can further affect the results.
Variation in pressure, nozzle adjustment and Improper environmental conditions can also change the results.
Benefits of Modern Automatic Water Resistance Testers
Now the modern water resistance testers like, Darong Fabric Waterproof Performance Tester YB 813G are more stable and accurate than traditional manual testers. Because these modern testers include digital pressure control from 6- 24 kpa +-0.2 kpa. Additionally, it includes automatic set test cycles that reduce the operator errors. The same flow of water on the fabric maintains the uniform intensity of rain.
These factors all improve the testing across various laboratories. The stable nozzles and fixed geometry of the equipment further contribute to testing efficiency, reducing variation caused by environmental conditions. These testers reduce the cost and time of rework, producing reliable water-resistance data for quality-control laboratories.
Buying Tips for AATCC Water Resistance Tester
Importance Factors for Textile Laboratories before Buying a Water Resistance Tester
To balance cost, precision, and testing efficiency, it is important to consider when buying a water resistance tester. Because manual testers are less expensive, they can produce more variation in results due to greater operator dependence.
On the other hand, the initial investment in a modern tester is high, but their testing methods are highly aligned with international standards and produce consistent results.
For Laboratories that handle a large number of samples, AATCC testers are most preferred. The testing standards demand uniform control of spray pressure. So, the testing equipment must support standardized testing.
Benefits of Darong YB 813G in Water Resistance Testing
The modern water resistance like, Darong Fabric Waterproof Performance Tester YB 813G are more stable and accurate than traditional manual testers. Because these modern testers include digital pressure control from 6- 24 kpa +-0.2 kpa. Additionally, it includes automatic set test cycles that reduce the operator errors.
The same flow of water over the fabric maintains a uniform rain intensity. These factors all improve the testing across various laboratories.
The stable nozzle spacing and fixed geometry of the equipment further enhance testing efficiency, reducing variation due to environmental conditions. These testers reduce the cost and time of rework, producing reliable water-resistance data.
Conclusion
The AATCC 35 rain resistance test is not just for meeting standards; it helps us, as laboratories, make critical decisions. It is the measure of water passing through fabric, expressed in grams. If the result exceeds 5 grams, the fabric has failed.
Traditional machines are manual and depend on the operator, which can lead to variation in the end results. On the other hand, modern equipment maintains a uniform pressure, producing repeatable results.
So, if laboratories test the fabric according to standards and using automated testers, they can better assess its performance under real-world conditions.
FAQS
What is the importance of 5 minutes of spray during the test?
The 5 minutes testing duration indicates the uniform exposure for all fabrics I.e. Every sample will be exposed in spray rain for 5 minutes, and we can compare the results of different fabrics across different textile laboratories.
Why is blotter weight used for getting final results instead of visual assessment?
By measuring the blotter weight, we can calculate the actual results by measuring the amount of water passed through the fabric.
How can pressure alter the water resistance test results?
Variations in pressure can change the intensity of rainwater, which can obscure the fabric’s actual performance. As the fabric fails at higher pressure, help us assess its performance in light or heavy rain.