ISO and ASTM are the two major international standards bodies for weathering and corrosion testing. Although they use different terms and organize the documents somewhat differently, they share very similar structures, and most other standards bodies follow the guidelines for standards used by ISO or ASTM.

In ASTM, four types of standards are used commonly in weathering and corrosion testing. Other standards bodies use formats similar to ASTM, although the terminology they use may not be exact.

A Standard Practice
standard states how you expose specimens to weathering/corrosion but not how long to run the test or how to evaluate the specimen after the test.

A Standard Test Method
states how long to run the test and/or how you evaluate specimens before/after testing, but usually does not give pass/fail criteria for the evaluation.

A Standard Specification
states how long to run a test and the pass/fail criteria for evaluations.

A Standard Guide
offers a wide array of test methods and practices for a particular material/product.

ASTM, ISO, and other standards usually comprise the following sections:

• The Scope briefly describes the topics included in the standard to help readers determine if the standard may be applicable to them. It is very important when determining whether a test is used for quality control, qualification, or correlative testing.
• References includes any documents specifically cited elsewhere in the standard.
• The Principle or Summary of Practice summarizes how the test is performed.
• The Significance and Use or Introduction is a critical section that apprises readers of a standard’s limitations and utility.
• The Reagents or Test Solutions section describes any chemicals required for the test
• The Apparatus section describes the hardware options for running a test.
• The Procedure/Evaluations section explains the details of performing a Weathering and Corrosion test and how evaluations should be performed.
• Report, and Precision and Bias details the information that must be included in a test report along with real-world data demonstrating the repeatability and reproducibility of the test method.
• Annexes and Appendices include supplementary information on a standard that doesn’t really fit into the rest of the standard document. These can be mandatory or non-mandatory (see FAQ on standards language)