ASTM D618 is the ASTM practice for conditioning plastics for testing. Because temperature and humidity strongly affect test results on plastics, it standardizes the conditions applied to specimens before and during testing so results can be compared across materials and laboratories. It does not necessarily require equilibrium, and a material specification that calls for the practice with changes takes precedence.
ASTM describes three aims of conditioning: bringing a material to equilibrium with normal room conditions, obtaining reproducible results regardless of prior exposure, or exposing it to abnormal conditions to predict service behavior. Since reaching equilibrium can take 20 to 100 days or more, conditioning for reproducibility is the approach used for purchase specifications and product control tests. Labs record the procedure used, as results may be higher or lower than equilibrium values.
Conditioning is done in an enclosure that holds controlled temperature and humidity for the required time. Our NG-EC Series environmental test chambers are used for conditioning plastic specimens to ASTM D618. If you need help matching ASTM D618 requirements to your parts or setup, contact our team.
