ASTM D685 Paper Conditioning

ASTM D685 – Standard Practice for Conditioning Paper and Paper Products. This practice is essential for consistency in test results when evaluating materials regardless of location or timing. The humidity of paper directly affects the physical performance. By conditioning paper to the standard atmospheric conditions, consistent, repeatable test results can be obtained. 

Paper products are known to be hygroscopic (able to absorb and release moisture) and their properties can change significantly depending on their moisture content. Therefore, it is essential to take into account the effect of humidity on the paper before conducting any tests to obtain reliable and accurate results.

ASTM D685 specifies the temperature (23 ± 1°C) and relative humidity (50 ± 2%) that paper samples should be conditioned at for at least 4 hours, but preferably for 24 hours, before testing. This allows the sample to reach a moisture equilibrium with the surrounding environment, leading to consistent and reproducible test results.

Overall, using ASTM D685 paper conditioning ensures that paper samples are tested under controlled conditions, eliminating the effect of environmental factors that could skew the results of the tests.

For this test method, there is a pre-conditioning requirement. This is important because the physical properties of a sample at 50% relative humidity depend upon whether the sample is brought to 50% from a higher or lower relative humidity. Purple Diamond has a whole resource center for conditioning. The conditioning and testing atmospheres are important because both temperature and humidity have significant effects on the physical properties of paper and board. 

1. Start by selecting a reliable and accurate temperature and humidity-controlled testing environment. Ensure that the location is equipped with a thermometer and hygrometer to monitor the temperature and humidity levels within the testing environment.

2. The testing environment must be maintained at a temperature of 23°C and a relative humidity of 50 percent.

3. Next, cut out sufficient pieces of ASTM D685 paper and place them in the testing environment on a flat surface.

4. Allow the paper to condition for at least 24 hours to allow it to equilibrate with the temperature and humidity in the testing environment.

5. After 24 hours, remove the paper from the testing environment and store it in a sealed container to prevent moisture from entering and altering the material properties. 

6. Use the conditioned paper to perform the required tests following the ASTM D685 standard protocols.

7. Record the test results and analyze them with respect to the required standards to determine if the paper meets the desired quality specifications.

This standard is for lack of a better word, technically, identical to TAPPI T402. The method is applied to define the standard conditioning, normal preconditioning, conditioning, and testing of paper and paper products, paperboard, fiberboard, and containers made from those sorts of products.