ASTM D685 Paper Conditioning

Testing Standard:

ASTM D685 Practice for Conditioning Paper and Paper Products

Standard Number

Standard Title
Practice for Conditioning Paper and Paper Products

Overview for ASTM D685:

ASTM D685 is a test method applied by setting up a standard atmosphere that all paper and paper products are conditioned to prior to testing. The purpose of conditioning is to establish a standard moisture content, temperature, and humidity level that allows for consistent and accurate testing of paper properties, such as strength, absorbency, and printability. Conditioning typically involves placing paper samples in a controlled environment for a specified period of time until they reach equilibrium with the surrounding air. The standard conditions for conditioning may vary depending on the specific test method and the type of paper being tested. Purple Diamond Testing offers ASTM D685 Testing as part of our packaging compliance and validation services.

Rationale for ASTM D685:

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. 

Key Points:

Related Standards:

At Purple Diamond, we offer a free consultation or a guided tour of our facilities. Consultations can be done over the phone or on zoom, so choose what suits you best. To get in touch, go to our Contact Us page and fill out the form or book an appointment using the calendar below. Our goal is to assist you in any way possible, so please don’t hesitate to contact us. Thank you so much for reading down this far and thank you for considering Purple Diamond as your dedicated testing, engineering, and design facility for all of your packaging needs.

Contact Us


Achieving ISO 17025 Accreditation is the pinnacle in third-party laboratory testing accreditation. It confirms that the facility has management, quality, and technical systems in place to ensure accurate and reliable analyses.
ISTA is revered as the certification standard for package testing for distribution. ISTA’s Testing Protocol remains a series of testing methodologies and standards well recognized within the packaging community.
A select few companies are authorized by PHMSA as an approved third-party packaging testing laboratory in accordance with Hazardous Materials Regulations, critical to ensuring safe transport of dangerous goods.


With over 12,000 standards globally, ASTM International’s fully transparent standards development enhances performance and confidence in consumer choices.
The Technical Association of Pulp and Paper Industry’s peer-reviewed standards improve production through operational methods and industry recognized best practices.


 The APASS program was designed by Amazon to help support vendors, sellers, and manufacturers in obtaining certification of their products as Frustration Free Packaging (FFP), Ships in Own Container (SIOC), or Prep-Free Packaging (PFP).


Your Concept, Our Expertise

Enter your contact information below to get in contact today

To View Our Accreditation, Please Fill Out This Form

ANAB ISO 17025 Accreditation Certificate

ANAB Accreditation Gated Form

  • This field is for validation purposes and should be left unchanged.

To View Our Accreditation, Please Fill Out This Form

ISTA Accreditation Certificate

ISTA Accreditation Gated Form

This field is for validation purposes and should be left unchanged.

To View Our Accreditation, Please Fill Out This Form

UN/DOT Accreditation Certificate

DOT Accreditation Gated Form

This field is for validation purposes and should be left unchanged.