ASTM D570: Water Absorption in Plastics

What is ASTM D570 Testing?

The test method, as specified in ASTM D570, is a standardized procedure for determining the water absorption of plastic materials when immersed under specified conditions. The test measures the amount of water absorbed by a plastic over a specific period of time under specified temperature conditions. It is beneficial because it characterizes the dimensional stability and also influences the electrical and mechanical properties of plastics when exposed to humid or wet conditions.

Testing according to ASTM D570 applies to all types of plastics, whether homogeneous or laminated, in sheet, rod, or molded forms. The results obtained account for the specific prediction of a plastic component’s performance during service, particularly under high-moisture exposure conditions.

Why is ASTM D570 Testing Important?

Water penetration testing is crucial for evaluating the suitability and durability of plastic materials in environments with high humidity, rainfall, or immersion. Plastics that absorb excessive water may swell, lose strength, or experience electrical failures.

ASTM D570 data is vital for:

• Quality control and specification compliance
• Material selection for moisture-exposed applications
• Predicting performance in marine, outdoor, or high-humidity settings
• Ensuring compliance with ASTM and ISO standards used across global industries.

Which Materials Can Be Tested Under ASTM D570?

This test method applies to a wide variety of thermoplastics and thermosetting materials, including:

• Polyethylene (PE)
• Polypropylene (PP)
• Nylon (PA)
• Polycarbonate (PC)
• Epoxy resins and phenolics
• Acrylics and polyesters

Typical forms tested:

• Molded specimens
• Sheets, rods, and tubes
• Laminated or cast materials

What Information Do ASTM D570 Test Results Provide?

The ASTM D570 test generates quantitative data that helps understand how plastics interact with water.

These results indicate how a plastic will perform in humid, marine, or wet service environments—especially for parts requiring dimensional precision or electrical insulation.

What Industries Use ASTM D570 Testing?

Water absorption testing is widely used across multiple sectors, including:

• Automotive – under-hood components, housings, and connectors
• Aerospace – composite structures and interior panels
• Electronics – insulating components and circuit board materials
• Construction – pipes, sheets, and waterproof materials
• Medical Devices – plastic housings and diagnostic equipment
• Consumer Goods – kitchenware, containers, and packaging
  

This testing ensures that materials remain reliable and dimensionally stable under exposure to moisture.

What Equipment Is Used for ASTM D570 Testing?

• Analytical balance: For high-precision weighing (accuracy of 0.001 g)
• Drying oven: To remove residual moisture
• Desiccator: For cooling specimens in a dry environment
• Water bath: Maintains constant immersion temperature
• Calipers or micrometers: For measuring specimen dimensions

How is the ASTM D570 Test Performed?

Step-by-Step Procedure

• Specimen Preparation:
  Samples are molded, machined, or cut into standard shapes—typically 50.8 mm diameter × 3.2 mm thick disks, or equivalent sizes, as these are generally standard.
• Drying and Cperiodtioning:
  Specimens are dried in an oven at a specified temperature (typically 50°C) for a defined period to remove existing moisture, and then cooled in a desiccator.
• Initial Weighing:
  Each sample is weighed immediately after cooling to obtain the dry weight (W₁).
• Immersion:
  Samples are submerged in distilled water at 23°C ± 1°C for 24 hours or at elevated temperatures as required.
• Removal and Surface Drying:
  After immersion, specimens are removed, gently wiped with a lint-free cloth, and quickly reweighed to obtain the wet weight (W₂).
• Calculation:
  Water absorption (%) = ((W₂ – W₁) / W₁) × 100

What Are the Standard Test Conditions?

These standardized conditions ensure repeatability and reproducibility, as well as comparable results across laboratories and materials, thereby facilitating accurate comparisons and comparisons between different materials.

Key Properties Measured

ASTM D 570 measures the percentage of water absorbed by a plastic sample after immersion in water. The result reflects the material’s ability to resist water penetration and indicates potential changes in weight, dimensions, strength, and appearance after exposure to water.

This test also provides a control method for material uniformity, which helps determine the influence of moisture on electrical insulation resistance and dielectric strength, as well as evaluate stability.

Related Testing Methods

• ISO 62 – Plastics: Determination of Water Absorption
• ASTM D5229 – Moisture Absorption Properties of Polymer Matrix Composites
• ASTM D1183 – Moisture Conditioning of Plastics
• ASTM D570-98 (Reapproved 2018) – Latest version for detailed procedures

Conclusion

ASTM D 570 is the standard test method for determining moisture absorption in plastic materials. This test assesses product reliability and performance in wet or humid environments. It measures water intake and observes changes in the material’s weight, dimensions, or appearance.

Material selection, product validation, and quality assurance, especially for component design used in challenging environments, are all based on data from ASTM D570. The test gives insight into the prediction of durability, stability, and long-time service performance of plastic materials.

Why Choose Infinita Lab for ASTM D570?

With Infinita Lab, you are guaranteed a Nationwide Network of Accredited Laboratories spread across the USA, the best Consultants from around the world, Convenient Sample Pick-Up and Delivery, and Fast Turnaround Time. 

Our team understands the stakes and subtleties of every test. Whether you’re validating a new Product, de-risking a prototype, or navigating complex compliance requirements, our specialists guide the process with rigor and clarity.  

Looking for a trusted partner to achieve your research goals? Schedule a meeting with us, send us a request, or call us at (888) 878-3090  to learn more about our services and how we can support you. 

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