Guide to the test standards for moisture permeability of silicone hip pads

Guide to the test standards for moisture permeability of silicone hip pads

In today’s global market, silicone hip pads are favored for their excellent performance and rich application scenarios. For independent sites engaged in the business of silicone hip pads, it is crucial to understand and master the test standards for moisture permeability of silicone hip pads. This can not only provide reliable product quality assurance for international wholesale buyers, but also enhance the competitiveness of the brand in the international market. This article will explore in depth the various test standards for moisture permeability of silicone hip pads, providing you with a comprehensive and detailed knowledge system.

1. The importance of moisture permeability test standards
Moisture permeability is one of the key indicators for measuring the performance of silicone hip pads. Good moisture permeability can ensure that the user’s buttocks skin can remain dry and comfortable during long-term use, reducing the discomfort caused by moisture and potential skin problems. For international wholesale buyers, they need to ensure that the purchased silicone hip pads meet the quality standards and user needs of the target market, and the moisture permeability test standards are an important basis for evaluating product quality.

2. Common moisture permeability test standards
(I) ISO standards
ISO 22649:2016《Footwear — Test methods for insoles and insocks — Water absorption and desorption》: This standard specifies the water absorption and dehydration test methods for footwear insoles and inner socks. During the test, the moisture permeability of the insole is evaluated by simulating the water absorption and drying of the insole in actual use. The specific method is to place the silicone hip pad sample in an environment with a certain humidity, and after a certain period of time, measure its weight change to obtain the water absorption rate and dehydration rate. This standard provides a scientific and quantifiable evaluation method for the moisture permeability test of silicone hip pads, which helps to compare the moisture permeability differences between different products.
ISO 14268:2019《Textiles — Fabrics for sportswear — Part 3: Determination of the moisture transmission properties》: This standard is mainly applicable to sportswear fabrics, but it also has a certain reference value for the moisture permeability test of silicone hip pads. It uses a dynamic method to test the moisture permeability of fabrics, that is, by maintaining certain temperature and humidity conditions in a closed test chamber, water vapor passes through the silicone hip pad sample, and then measures the water vapor permeation on the other side. This method can more realistically simulate the process of heat and moisture generated by human activities passing through the silicone hip pad in actual use, so as to more accurately evaluate its moisture permeability.
(II) JIS standard
JIS L1099 B1: This is a moisture permeability test standard widely used in materials such as textiles and leather. For silicone hip pads, the test principle is to place the sample in a moisture permeable cup, and then place the moisture permeable cup in an environment with certain temperature and humidity conditions. The amount of water vapor passing through the silicone hip pad is calculated by measuring the weight change of the moisture permeable cup within a certain period of time. This standard sets corresponding moisture permeability indicators according to different materials and usage requirements, such as moisture permeability greater than 10000g/m²·24h, etc. This standard has been widely used in Asia, especially in the Japanese and Chinese markets, providing a unified testing and evaluation method for silicone hip pad manufacturers and buyers.
(III) AATCC Standard
AATCC 127《Water Resistance: Hydrostatic Pressure Test》: Although this standard is mainly used to test the water pressure resistance of fabrics, its test principles and methods can also provide some reference for the moisture permeability test of silicone hip pads. During the test, a certain water pressure is applied to the silicone hip pad sample to observe whether water can pass through the sample. This can indirectly evaluate the moisture permeability of the silicone hip pad when facing a certain liquid pressure, especially in some special application scenarios, such as medical care, outdoor sports, etc., the silicone hip pad may be exposed to liquid, and its water pressure resistance is closely related to its moisture permeability. The AATCC 127 standard provides a reference method for evaluating the performance of silicone hip pads in these scenarios.
(IV) ASTM Standard
ASTM E96《Standard Test Methods for Water Vapor Transmission of Materials》: This standard provides a variety of methods for testing the water vapor transmission rate of materials, including steady-state method and dynamic method. The steady-state method measures the value of the amount of water vapor passing through the silicone hip pad when it reaches a steady state under constant temperature and humidity conditions; the dynamic method tracks the change of water vapor permeability over time under changing environmental conditions. The ASTM E96 standard specifies in detail the requirements for test equipment, test conditions, sample preparation, and data processing, ensuring the accuracy and reliability of the test results. This standard is widely used in Europe and the United States for moisture permeability testing of various materials, including consumer products such as silicone hip pads, and is one of the standards commonly used by international wholesale buyers when evaluating product quality.
(V) GB/T standard
GB/T 1873-2010 “Leather for shoe uppers”: This standard specifies the moisture permeability of leather for shoe uppers, and some of the test methods and index requirements can also be applied to silicone hip pads. For example, the standard specifies the test method for water vapor permeability, that is, using a sample of a certain area, under specific temperature and humidity conditions, to measure the amount of water vapor passing through the sample per unit time. Through the test method of this standard, the moisture permeability of silicone hip pads can be quantitatively evaluated, thereby providing a quality basis for silicone hip pads produced and sold domestically, and it is also convenient to align and compare with international standards.

3. Detailed explanation of the test method
(I) Moisture permeability test method
Principle: Under specific temperature and humidity conditions, water vapor will diffuse from the high humidity side to the low humidity side through the silicone hip pad. By measuring the mass of water vapor that permeates the unit area of ​​the silicone hip pad per unit time, its moisture permeability can be obtained.
Test equipment: Moisture permeability cups, balances, constant temperature and humidity chambers and other equipment are usually used. The moisture permeability cup is used to place the silicone hip pad sample and maintain a certain humidity environment in the cup; the balance is used to accurately measure the mass change of the moisture permeability cup; the constant temperature and humidity chamber provides stable temperature and humidity conditions for the entire test process.
Test steps:
Cut the silicone hip pad sample into a suitable size, place it on the moisture permeability cup, and ensure that the sample and the moisture permeability cup are well sealed.
Place the permeable cup containing the sample in a constant temperature and humidity chamber, and set the temperature and humidity conditions required for the test, such as temperature 38℃, relative humidity 90%, etc.
During the test, take out the permeable cup at regular intervals (such as 24 hours), weigh its mass with a balance, and record the data.
According to the mass change data, calculate the amount of water vapor that permeates the silicone hip pad per unit area per unit time, that is, the moisture permeability. Through multiple tests and calculations, the average moisture permeability of the silicone hip pad can be obtained, and compared with relevant standards to evaluate whether its moisture permeability meets the requirements.
(II) Water pressure resistance test method
Principle: Apply gradually increasing water pressure to the silicone hip pad to observe when water begins to permeate the sample. The magnitude of the water pressure reflects the moisture permeability resistance of the silicone hip pad when facing liquid pressure, that is, the water pressure resistance. The higher the water pressure resistance, the better the silicone hip pad can prevent water from passing through to a certain extent, while allowing internal moisture to be discharged, thus having a better balance of moisture permeability.
Test equipment: The main tester used is a water pressure tester, which can accurately control the application of water pressure, and can monitor and record the water pressure value and the water permeability of the sample in real time.
Test steps:
Fix the silicone hip pad sample on the test fixture of the water pressure tester to ensure that the sample is flat and well sealed.
Turn on the tester and gradually increase the water pressure according to the set water pressure increment rate, such as 50mmH2O per minute.
Observe the surface of the silicone hip pad sample. When the first drop of water appears, record the water pressure value at this time, which is the water pressure resistance value of the sample. By comparing with the water pressure resistance index specified in the standard, judge whether the moisture permeability of the silicone hip pad is qualified.
(III) Dynamic method test
Principle: Simulate the continuous changes in human activities and environmental conditions in the actual use environment. In a closed test system, water vapor is allowed to pass through the silicone hip pad under a certain temperature and humidity gradient, and the changes in water vapor permeability over time are continuously monitored and recorded, so as to more comprehensively evaluate the moisture permeability of the silicone hip pad.
Test equipment: Dynamic method moisture permeability tester, which consists of a test chamber, a temperature and humidity control system, a water vapor generation system, a data acquisition system, etc. The test chamber is used to place the silicone hip pad sample and maintain good sealing; the temperature and humidity control system can accurately adjust the temperature and humidity conditions in the test chamber; the water vapor generation system provides a stable water vapor source for the test; the data acquisition system monitors and records relevant parameters such as water vapor permeability in real time.
Test steps:
Install the silicone hip pad sample in the test chamber of the dynamic method moisture permeability tester to ensure that the sample is installed flat and the seal is reliable.
Set the test conditions, such as the temperature on one side of the test chamber is 35℃ and the relative humidity is 70%, and the temperature on the other side is 25℃ and the relative humidity is 50%, etc., to form a certain temperature and humidity gradient to promote water vapor to pass through the silicone hip pad.
Start the tester to allow water vapor to pass through the silicone hip pad under the set temperature and humidity conditions, and continuously record the curve of water vapor permeability over time through the data acquisition system.
The data obtained from the test is analyzed and processed to calculate the moisture permeability performance parameters of the silicone hip pad under dynamic conditions, such as the average moisture permeability rate, moisture permeability coefficient, etc., and compared with relevant standards or product technical requirements to determine whether its moisture permeability performance meets the standards.

4. Factors Affecting Moisture Permeability
(I) Silicone Material Characteristics
Molecular structure: The molecular structure of silicone has an important influence on its moisture permeability. The flexibility of the siloxane chain segment is good, which can provide a certain channel for the diffusion of water vapor molecules. If other groups are introduced into the silicone material or special chemical modifications are performed, the interaction force and free volume between its molecules may be changed, thereby affecting the permeability of water vapor. For example, silicone materials containing hydrophilic groups may improve moisture permeability, while silicone materials with excessive cross-linking may reduce moisture permeability because the cross-linking points will hinder the diffusion of water vapor molecules.
Crystallinity: The crystallinity of silicone materials will also affect moisture permeability. The molecules in the crystalline region are arranged more tightly, and it is difficult for water vapor molecules to penetrate, while the non-crystalline region is relatively loose and easy to form diffusion channels. Therefore, silicone hip pads with lower crystallinity usually have better moisture permeability. In the production process, by controlling the formula and processing technology of silicone, its crystallinity can be adjusted to optimize the moisture permeability.
(II) Production process
Molding process: Different molding processes will affect the microstructure of the silicone hip pad, thereby affecting the moisture permeability. For example, during the injection molding process, process parameters such as mold temperature, injection pressure, and holding time will affect the filling and molecular orientation of the silicone material. If the mold temperature is too high or the injection pressure is too low, pores or defects may appear inside the silicone material. These pores may become channels for rapid diffusion of water vapor, thereby improving moisture permeability; however, too many pores may also reduce the mechanical properties and appearance quality of the product. Therefore, it is necessary to optimize the molding process parameters to obtain a good balance between moisture permeability and comprehensive performance.
Post-processing process: The post-processing process of the silicone hip pad also has a certain effect on its moisture permeability. For example, the degree of vulcanization treatment will affect the cross-linking density of silicone. Appropriate vulcanization treatment can form a stable cross-linking network between the silicone molecular chains, improve the mechanical properties and heat resistance of the product, but excessive vulcanization may increase the cross-linking density and reduce moisture permeability. In addition, surface treatment processes, such as coating and printing, may also form a barrier layer on the surface of the silicone hip pad, hindering the permeation of water vapor, thereby reducing the moisture permeability. Therefore, when performing the post-processing process, it is necessary to fully consider its impact on moisture permeability and take corresponding measures to optimize it.
(III) Additives
Fillers: Adding fillers to silica gel can improve its mechanical properties, heat resistance, wear resistance, etc., but the type and amount of fillers will also affect the moisture permeability. Generally speaking, the smaller the particle size of the filler and the more it is used, the higher the density of the silica gel material, the more difficult it is for water vapor to pass through, and the lower the moisture permeability. For example, a silica gel hip pad with a large amount of nano-silica filler added may have lower moisture permeability than a silica gel hip pad without filler. Therefore, when selecting fillers, it is necessary to weigh the improvement effect of the filler on performance and the negative impact on moisture permeability to meet the comprehensive performance requirements of the product.
Plasticizers: The addition of plasticizers can improve the flexibility and processability of silica gel, but it will also affect moisture permeability. Plasticizer molecules usually have a certain degree of hydrophilicity and can interact with water vapor molecules, thereby changing the moisture permeability of silica gel materials. An appropriate amount of plasticizer can increase the free volume and intermolecular distance inside the silicone, provide more channels for the diffusion of water vapor molecules, and improve moisture permeability; however, excessive plasticizer may cause the mechanical properties of silicone materials to deteriorate, and the plasticizer may gradually migrate to the surface of the material, affecting the appearance and performance stability of the product. Therefore, it is necessary to reasonably control the type and amount of plasticizer to achieve a good balance between moisture permeability and other properties.

5. How to choose a suitable moisture permeability test standard
(I) Choose according to the target market
European and American market: If the main sales market of silicone hip pads is Europe and the United States, then standards such as ASTM E96 and ISO 22649 will be more appropriate choices. These standards have been widely recognized and applied in Europe and the United States, and meet local quality certification systems and regulatory requirements. For example, in the United States, many buyers and retailers require products to pass the ASTM E96 standard test to ensure that the product’s moisture permeability meets consumer needs and safety standards.
Asian Market: For the Asian market, especially the Japanese and Chinese markets, standards such as JIS L1099 B1 and GB/T 1873-2010 are more applicable. These standards have a high degree of popularity and recognition among local enterprises and consumers, and can better meet the quality evaluation and testing requirements of the local market. For example, in Japan, the moisture permeability test of textiles and leather products usually adopts the JIS L1099 B1 standard, so if silicone hip pad companies want to enter the Japanese market, they need to ensure that their products meet the requirements of this standard.
(II) Selection according to product application areas
Medical care field: In the medical care field, silicone hip pads are usually used for long-term bedridden patients, postoperative rehabilitation patients, etc., to keep the patient’s buttocks skin dry and comfortable, and prevent the occurrence of skin problems such as pressure sores. For this type of product, in addition to considering the general moisture permeability test standards, it is also necessary to pay attention to the stability of its moisture permeability performance under special conditions such as high humidity and long-term use. For example, you can refer to the dynamic method test in the ISO 14268 standard to simulate the temperature and humidity changes and patient activities in the hospital environment, and conduct strict moisture permeability tests on silicone hip pads to ensure their effectiveness and reliability in practical applications.
Outdoor sports field: In the field of outdoor sports, silicone hip pads are often used in sports protective gear, outdoor seats and other products to provide comfortable sitting and good breathability. Due to the complex and changeable outdoor environment and the large difference in humidity conditions, it is necessary to select a moisture permeability test standard that can simulate outdoor environmental conditions. For example, the dynamic method test in the ASTM E96 standard can better simulate the process of heat and moisture generated by human activities in outdoor sports passing through the silicone hip pad, thereby providing a more accurate basis for evaluating the moisture permeability of the product. In addition, you can also refer to the water pressure resistance test method in the AATCC 127 standard to ensure that the silicone hip pad can still maintain a certain moisture permeability when encountering rain, sweat, etc., to prevent internal water accumulation from causing discomfort to the user.
(III) Selection based on the company’s own situation
Production capacity and equipment conditions: The company’s own production equipment and testing capabilities are also one of the important factors in selecting the moisture permeability test standard. If the company has advanced moisture permeability test equipment and professional testing personnel, and can test according to a variety of international standards, then some standards with high test accuracy and comprehensive evaluation can be selected, such as ISO 22649 and ASTM E96. Although these standards have high requirements for test equipment and operation, they can provide companies with more accurate and reliable product quality data, which helps to improve the market competitiveness of products. However, if the company’s equipment conditions and testing capabilities are limited, relatively simple and easy-to-use test standards, such as JIS L1099 B1, can be selected to reduce the cost and difficulty of testing while ensuring that product quality meets basic requirements.
R&D and innovation needs: For companies that focus on R&D and innovation, the selection of moisture permeability test standards also needs to consider their guiding role in product improvement and innovation. For example, if an enterprise is developing a new type of high moisture permeability silicone hip pad material, it can choose some standards that can deeply analyze the relationship between the material’s moisture permeability and molecular structure, production process and other factors, such as ISO 14268. Through in-depth research and application of these standards, enterprises can better understand the performance characteristics and shortcomings of products, provide strong technical support for optimizing product formulas and production processes, and promote continuous innovation and development of products.

6. Application of moisture permeability test in quality control
(I) Raw material procurement link
Supplier evaluation: When purchasing silicone raw materials, enterprises can require suppliers to provide raw material moisture permeability test reports and evaluate the moisture permeability of raw materials according to relevant test standards. By comparing the raw material test data provided by different suppliers, select suppliers whose moisture permeability meets product requirements and whose quality is stable to cooperate, so as to ensure the moisture permeability quality of silicone hip pads from the source.
Raw material quality inspection: Before the raw materials are put into storage, enterprises can conduct random inspections on the raw materials according to the selected moisture permeability test standards. If the test finds that the moisture permeability of the raw materials does not meet the requirements, the supplier should be communicated and negotiated in time to find solutions, such as return or adjustment of the production process, so as to avoid the subsequent production of silicone hip pads that are unqualified due to raw material quality problems, causing greater economic losses.
(II) Production process monitoring
Process parameter optimization: During the production process of silicone hip pads, regular moisture permeability tests can monitor the impact of changes in production process parameters on the moisture permeability of products. For example, during the injection molding process, a batch of small sample products are produced by changing parameters such as mold temperature and injection pressure, and moisture permeability tests are carried out according to the test standards. The process parameters are adjusted according to the test results to find the optimal production conditions to ensure that the moisture permeability of the product reaches the best state. At the same time, by real-time monitoring of moisture permeability performance indicators, abnormal situations that may occur in the production process, such as equipment failure, raw material fluctuations, etc., can be discovered in time, and corresponding measures can be taken to adjust and correct them to ensure the stability and consistency of product quality.
Production batch quality control: The moisture permeability of each production batch of silicone hip pads is tested to establish a product quality file. By statistically analyzing the moisture permeability data of different batches of products, the overall stability of the production process and the degree of dispersion of product quality can be evaluated. If it is found that the moisture permeability of a batch of products fluctuates significantly or is unqualified, the relevant records in the production process can be traced back in time to find out the problem, and the batch of products can be properly handled, such as rework, scrapping, etc., to prevent unqualified products from entering the market and maintain the good reputation and brand image of the company.
(III) Finished product inspection and delivery
Finished product quality determination: After the silicone hip pad is produced, the finished product is fully inspected in accordance with the relevant moisture permeability test standards. Compare the test results with the product standard requirements to determine whether the product is qualified. Only products whose quality indicators such as moisture permeability meet the standard requirements can be allowed to be sold from the factory to ensure that the silicone hip pads provided to consumers have reliable moisture permeability and comfort.
Quality traceability and improvement: For silicone hip pad products that have been shipped, if complaints or problems about moisture permeability are received in market feedback or after-sales service, the company can use the previously established quality files to quickly trace the production batch, raw material source, production process and other information of the product, and conduct in-depth analysis of the cause of the problem. According to the analysis results, formulate corresponding improvement measures, such as optimizing product design, improving production process, strengthening raw material quality control, etc., to continuously improve the quality level of products and meet consumers’ needs and expectations for the moisture permeability of silicone hip pads.

7. Development trend of international moisture permeability test standards
(I) Intelligent and automated test methods
With the continuous advancement of science and technology, moisture permeability test methods are developing in the direction of intelligence and automation. New moisture permeability test instruments are equipped with advanced sensor technology, automatic control systems and data processing systems, which can realize the full automation of the test process, reduce human errors and cumbersome operation. For example, some dynamic moisture permeability testers can automatically adjust the temperature and humidity conditions in the test chamber, monitor the water vapor transmission rate in real time, and automatically record and generate test reports. This not only improves the test efficiency and accuracy, but also can quickly analyze and process a large amount of test data, providing more powerful support for product quality assessment and research and development.
(II) Coordination and unification and internationalization of standards
In the context of global economic integration, trade between countries is becoming more and more frequent, and the need for coordination and unification and internationalization of product quality standards is becoming increasingly urgent. Authoritative organizations such as the International Organization for Standardization (ISO) are working hard to promote the internationalization of moisture permeability test standards and promote mutual recognition and coordination of standards between different countries and regions. For example, in the formulation process, standards such as ISO 14268 and ISO 22649 fully considered the technical level, market demand and industry characteristics of different regions in the world, and tried to adopt common test principles and methods to make them more applicable and comparable globally. In the future, with the continuous strengthening of international cooperation and exchanges, moisture permeability test standards are expected to further achieve global unification, reduce the international trade costs of enterprises, and improve the international recognition of product quality.
(III) Refinement and personalization of test standards
With the increasing diversification and personalization of consumer needs and the continuous expansion of industry application fields, moisture permeability test standards are also gradually refined and personalized. For different types of products, different usage scenarios and different consumer groups, formulate more specific, detailed and personalized moisture permeability test standards and specifications. For example, for medical silicone hip pads, more attention may be paid to the stability of its moisture permeability under high humidity and long-term use conditions and its non-irritation to the skin; while for silicone hip pads for outdoor sports, emphasis will be placed on its waterproof and moisture permeability balance under complex environmental conditions. This refined and personalized standard development trend can better meet the differentiated needs of the market and consumers, and promote product innovation and quality improvement in the silicone hip pad industry.

8. Case Analysis
(I) Case 1: Water Permeability Test and Quality Improvement of Silicone Butt Pads of a Well-known Medical Supplies Company
Background: The silicone butt pads produced by the company are mainly used in the field of medical care, especially to provide comfortable support and skin protection for long-term bedridden patients. However, after the product was put on the market, some users reported that after a period of use, the skin on the buttocks of the patients became damp and red, which was suspected to be related to the water permeability of the silicone butt pads.
Testing process: The company immediately organized technical personnel to test the water permeability of the silicone butt pads according to the dynamic method in the ISO 14268 standard. During the test, it was found that the water permeability of the product was lower than the minimum requirement specified in the standard, indicating that its water permeability was insufficient and could not meet the patient’s skin needs for dryness and comfort in the medical care environment.
Problem analysis: Through further analysis of the production process and raw materials, it was found that the company added a new filler to the silicone material to improve the mechanical properties of the product, but the addition of the filler affected the molecular structure and water permeability of the silicone.
Improvement measures: The company adjusted the formula of the silicone material, reduced the amount of filler while maintaining good mechanical properties, and optimized the production process parameters. After retesting, the moisture permeability of the improved silicone hip pad reached the requirements of the ISO 14268 standard, the problems reported by users were effectively solved, the product quality was significantly improved, and the market share was further expanded.
(II) Case 2: Water pressure resistance and moisture permeability balance test of a silicone hip pad of an outdoor product brand
Background: The brand launched a new outdoor sports seat, and its built-in silicone hip pad needs to have a good balance of waterproof and moisture permeability to cope with the complex and changeable outdoor weather conditions and the activity needs of users. In the product design stage, the company needs to determine the water pressure resistance and moisture permeability indicators of the silicone hip pad, and select appropriate test standards for evaluation.
Test process: The company refers to the AATCC 127 standard to test the water pressure resistance of the silicone hip pad, and uses the dynamic method in the ASTM E96 standard to test its moisture permeability. After many tests and adjustments, the water pressure resistance value and moisture permeability range of the silicone hip pad were finally determined to ensure that when the product is used outdoors, it can effectively prevent external moisture such as rain and sweat from penetrating, and can also allow internal moisture to be discharged smoothly to maintain the comfort of the user.
Results and Application: After strict testing and quality control, the brand’s outdoor sports seats have been widely praised by consumers after they were launched on the market, and the good waterproof and moisture permeability of its silicone hip pad has become a major selling point of the product. In subsequent product development, the company continues to use this set of testing standards and quality control systems, and continuously launches outdoor products with better performance and more reliable quality, which enhances the brand’s competitiveness and influence in the market.

9. Summary
The moisture permeability of the silicone hip pad is one of the key factors affecting its performance and market competitiveness. Understanding and mastering various moisture permeability test standards is of great significance for independent stations to carry out silicone hip pad business and expand international markets. Through in-depth analysis of common moisture permeability test standards, including ISO, JIS, AATCC, ASTM and GB/T, as well as detailed discussions on test methods, influencing factors, standard selection, quality control applications and international development trends, we are able to provide comprehensive and systematic guidance for the production and sales of silicone hip pads. In the actual operation process, enterprises should reasonably select moisture permeability test standards according to their own conditions, target markets and product application areas, and apply them to various links such as raw material procurement, production process monitoring, and finished product inspection to ensure that product quality meets international requirements and meets consumer needs, so as to stand out in the fierce international market competition and achieve sustainable development.