The full title of the standard is . It was officially published on July 15, 2021 and is the most recent version of the standard, developed by the ASTM International Committee D20 on Plastics.
Standard Practice for Conditioning and Testing Plastics
Yes. Section 6 allows for alternative conditions (e.g., 23°C/75% RH for tropical simulations), but you must explicitly note the deviation from the standard atmosphere.
ASTM D618-21 acts as a default guideline [1.16]. If a specific material standard—such as ASTM D638 for tensile properties or ASTM D4000 for classification—mandates a modified conditioning step, that material specification over ASTM D618 [1.16, 1.22]. Comparison with ISO 291
Ensures the physical values generated in the lab are true to the material's properties at the specified conditions. astm d618-21 pdf
High-humidity exposure to test electrical insulation resistance [1.17]. Standard Test Conditions (The "Room" Environment)
A: The 2021 revision tightens humidity tolerances, clarifies test time limits, and updates referenced standards.
Plastics are hygroscopic or hydrophobic to varying degrees. Nylon absorbs moisture from the air, becoming more flexible and impact-resistant. Polycarbonate, on the other hand, can become brittle if too dry. Without a standard like ASTM D618, one laboratory might test "dry-as-molded" nylon while another tests nylon conditioned at 50% RH. The results would disagree by 50% or more.
D618-21 requires that testing occur in the same environment as conditioning, unless otherwise specified (e.g., high-temperature testing). The full title of the standard is
In the world of materials testing, consistency is king. Without standardized conditions, a single plastic material could yield three different strength results on three different days simply because of humidity or temperature changes. This is where becomes indispensable.
To ensure that test results are accurate and reproducible across different laboratories globally, the industry relies on a fundamental standard: . The latest active revision of this standard is ASTM D618-21 .
A word of caution: Many websites offer "free" ASTM PDFs. These are often:
Without proper conditioning, test results can be misleading. For instance, a moisture-sensitive plastic like Nylon (PA) will test differently at 20% relative humidity (RH) compared to 65% RH. eliminates this variable. Section 6 allows for alternative conditions (e
– Many have site licenses to ASTM standards.
Many material specifications require tighter tolerances, down to 23°C ± 1°C and 50% ± 5% RH.
Conditioning at 23°C and 50% RH for a specified time (often 40 hours or more).