For any engineer, lab technician, or quality control manager working with polymers, ASTM D618-21 is not just a suggestion—it is a prerequisite for valid data. Proper conditioning eliminates environmental variables, ensuring that the data you record reflects the material's true properties, not just the weather in your lab that day.
Disclaimer: This blog post is for informational purposes only. Always refer to the official ASTM D618-21 document published by ASTM International for precise testing protocols.
The ASTM D618-21 standard, titled "Standard Practice for Conditioning Plastics for Testing," defines the procedures for conditioning plastic materials to ensure reproducible test results. Because temperature and humidity significantly affect the physical and electrical properties of plastics, this standard provides a consistent baseline for material comparisons across different laboratories. Key Conditioning Procedures
The standard outlines several specific procedures based on the testing requirements:
Procedure A (Standard): Specimens are conditioned in a standard laboratory atmosphere of 23 ± 2°C (73.4 ± 3.6°F) and 50 ± 10% relative humidity for at least 40 hours.
Procedure B: Involves oven conditioning followed by desiccation to remove moisture.
Procedure C: Requires immersion in water at a specific temperature.
Procedure D: Focuses on conditioning in high-humidity environments. Critical Specifications
Equilibrium: While the goal is to stabilize specimens, the standard notes that reaching full equilibrium can take 20 to 100 days or more depending on material thickness.
Standard Atmosphere: Defined as 23°C (73.4°F) and 50% relative humidity.
Precedence: If a specific ASTM material specification (found in ASTM D4000) exists for a plastic, it takes precedence over the general D618 procedures. Accessing the PDF
ASTM D618-21 is a copyrighted document. You can obtain the official version through the following authorized distributors: ASTM D618-21.pdf
ASTM D618-21 is the current standard practice for conditioning plastics for testing. Published in July 2021, it establishes standardized temperature and humidity conditions to ensure reproducible results across different laboratories and materials. Core Conditioning Procedures
The standard defines several specific procedures based on the material's requirements: Procedure A: Standard laboratory atmosphere (typically relative humidity). Procedure B: Oven conditioning followed by desiccation. Procedure C: Conditioning via water immersion. Procedure D: Exposure to high humidity conditions. Key Significance
Reproducibility: Standardizes conditions so that physical and electrical property tests (which are highly sensitive to temperature and moisture) can be reliably compared.
Equilibrium: While conditioning aims to bring materials into equilibrium with room conditions, some materials may require 20 to 100+ days to reach true substantial equilibrium depending on thickness.
Precedence: If a specific material specification exists (e.g., under ASTM D4000), that specification's requirements take precedence over D618. Accessing the Full Document
ASTM standards are copyrighted and typically require a purchase. You can find the official document and related "Redline" versions (which highlight changes from the previous 2013 version) at these official distributors:
ASTM International: The primary source for the standard and digital subscriptions. astm d618-21 pdf
ANSI Webstore: Provides the standard in PDF format with Digital Rights Management (DRM).
Accuris (formerly IHS Markit): Offers various formats and historical versions.
Standard Practice for Conditioning Plastics for Testing - ASTM
ASTM D618-21 establishes standard procedures for conditioning plastic materials to ensure accurate and reproducible results for physical, electrical, and mechanical tests. This standard defines environmental requirements, such as a standard laboratory atmosphere of 23°C and 50% relative humidity, to equilibrate test specimens before evaluation. For more details, visit ASTM International
Standard Practice for Conditioning Plastics for Testing - ASTM
ASTM D618-21 sets the mandatory standard for conditioning plastics, ensuring reliable, comparable material testing by controlling temperature and humidity to eliminate environmental variability. It establishes protocols like Procedure A (40-hour conditioning) to standardize mechanical property evaluations, which are critical for quality control in manufacturing and material research. Purchase the standard from the official ASTM International website.
Myth 1: "It only applies to mechanical testing." False. ASTM D618-21 explicitly covers electrical, optical, and even thermal testing.
Myth 2: "Room temperature is fine." No. "Laboratory ambient" varies daily. D618-21 requires a controlled chamber, not a room air conditioner.
Myth 3: "Older revisions are good enough." Accreditation bodies (A2LA, UKAS, NABL) now reference D618-21. If your quality manual says "D618-13," you are non-conforming.
Title: Standard Practice for Conditioning and Testing Plastics
Published by: ASTM International (formerly known as the American Society for Testing and Materials)
Release Date: 2021
Summary:
ASTM D618-21 is a standard practice that provides guidelines for conditioning and testing plastics. The standard outlines the procedures for conditioning plastics prior to testing, as well as the testing conditions to be used for various types of plastics.
Key Points:
Significance:
The ASTM D618-21 standard is significant because it provides a standardized approach to conditioning and testing plastics. This helps to ensure that test results are consistent and comparable across different laboratories and testing facilities.
Benefits:
Limitations:
Target Audience:
The ASTM D618-21 standard is intended for use by:
Overall:
The ASTM D618-21 standard provides a valuable resource for those involved in the testing of plastics. By following a standardized approach to conditioning and testing plastics, test results are more likely to be accurate and reliable. However, users should be aware of the limited scope and complexity of the standard.
ASTM D618-21 is the definitive standard for the conditioning of plastic materials before they undergo mechanical, electrical, or thermal testing. Because the physical properties of plastics are highly sensitive to environmental factors, this practice ensures that test results are reproducible and comparable across different laboratories.
The current version, ASTM D618-21, was approved on July 15, 2021, and replaces previous iterations like D618-13. You can purchase and download the official ASTM D618-21 PDF directly from the ASTM International website. Purpose of Conditioning Conditioning serves three primary goals:
Equilibrium: Bringing a material into a stable state with normal room conditions.
Reproducibility: Eliminating the influence of a material's previous exposure history (e.g., storage in a hot warehouse) to ensure consistent data.
Service Prediction: Subjecting specimens to extreme temperature or humidity to simulate real-world service environments. Key Conditioning Procedures
ASTM D618 defines several specific procedures labeled by letters. The choice of procedure depends on the material type and the final test to be performed: Environment Typical Duration Procedure A Standard Lab Atmosphere (23°C, 50% RH) Min. 40 hours Procedure B Oven conditioning at 50°C Procedure C Immersion in distilled water (23°C) Procedure D High humidity (96% RH at 23°C) Procedure E High temperature water immersion (50°C) Standard Lab Atmosphere
The most common environment used for Procedure A is the "Standard Laboratory Atmosphere". It is strictly defined as:
Standard Practice for Conditioning Plastics for Testing - ASTM
ASTM D618-21 provides essential, standardized protocols for conditioning plastic and electrical insulating materials, ensuring consistent temperature and humidity environments for accurate testing. The 2021 standard mandates specific conditions—notably Procedure A at 23±2°C and 50±5% humidity—to ensure reproducible results across diverse laboratory settings. For direct access to the standard document, view the file at Antpedia. ASTM D618-21.pdf
ASTM D618-21 establishes standard procedures for conditioning plastic specimens to ensure reproducible test results by controlling temperature and humidity, with Procedure A commonly requiring 40-88 hours at 23°C and 50% relative humidity. This practice is essential for stabilizing physical and electrical properties across various lab environments. The official standard can be purchased and downloaded at ASTM International.
Report: ASTM D618-21 Standard Practice for Conditioning Plastics for Testing 1. Executive Summary
ASTM D618-21 ("Standard Practice for Conditioning Plastics for Testing") is the critical industry standard for preparing plastic specimens prior to physical, mechanical, or electrical testing. It defines precise procedures for controlling temperature and relative humidity (RH) to ensure reliable, reproducible test results and to eliminate variability caused by previous environmental exposure. This standard ensures that materials are brought into a known, consistent state before testing, often allowing for comparisons between laboratories. 2. Scope and Purpose
Purpose: To standardize the atmosphere (temperature and humidity) to which plastics are subjected before and during testing. For any engineer, lab technician, or quality control
Applicability: Applies to most plastics, including molding materials, sheets, and finished products, prior to tests such as tensile strength, flexural properties, and dielectric strength.
Equilibrium: While often intended to achieve equilibrium, the procedures focus on providing a consistent conditioning baseline, acknowledging that full equilibrium might take 20–100+ days. 3. Key Conditioning Procedures
ASTM D618-21 defines several specific procedures (Procedures A through E) to simulate various service environments: Procedure A (Standard Lab Atmosphere): Condition at Relative Humidity. Duration: 40 hours for thickness ≤is less than or equal to 7 mm, 88 hours for > 7 mm. Procedure B (Oven Conditioning): Conditioning in an oven at for 48 hours, followed by cooling in a desiccator.
Procedure C (Water Immersion): Immersion in distilled water at for 48 hours, followed by cooling in water to Procedure D (High Humidity): Conditioning at
Alternative Specifications: If a material specification differs from this practice (e.g., in ASTM D4000), the material specification takes precedence. 4. Significance and Use
Reproducibility: Eliminates the impact of previous exposure history.
Service Prediction: Subjects material to specific humidity/temperature conditions to predict long-term performance.
Quality Control: Crucial for standardizing material performance during QC checks.
International Alignment: Comparable to ISO 291, though ASTM D618-21 is recognized for being more adaptable and precise. 5. Technical Requirements Temperature: Standard laboratory temperature is Humidity: Standard laboratory relative humidity is
Time: Specified periods (e.g., 40h or 88h) depend heavily on the thickness of the material.
Safety: The standard notes it does not address all safety concerns associated with its use, particularly when using high-temperature ovens or high humidity chambers. 6. Accessing the Document
The official ASTM D618-21 PDF can be purchased and downloaded through the ASTM International Website or ANSI Webstore.
Disclaimer: This report is a summary for informational purposes based on 2026 data. Always refer to the official, current version of the standard.
Specific conditioning requirements for a certain plastic type (e.g., Nylon vs. PE)?
Procedures for creating an accurate summary of the 2025 revision discussions? Let me know what details you need to complete your report.
Standard Practice for Conditioning Plastics for Testing - ASTM
Defines that the practice applies to both rigid and semi-rigid plastics, but notes exceptions for materials where a specific test method requires unique conditioning.
Failing to condition specimens can lead to: Disclaimer: This blog post is for informational purposes
One well-known case involved nylon gears that cracked in the field because the supplier tested them as-molded (dry-as-molded) rather than conditioning them to equilibrium per D618-21. The dry-as-molded strength was 30% higher than the conditioned strength—a disastrous overestimation.