ASTM E104

ASTM E104 is the ASTM standard practice for maintaining constant relative humidity by means of aqueous solutions. It is used to help create controlled humidity conditions with solution-based methods, supporting consistent environmental exposure and testing. This matters when a stable relative humidity level is needed for product evaluation, conditioning, or comparative testing. By defining a recognized practice, ASTM E104 helps improve repeatability and reduces uncertainty in humidity-sensitive work.

What is ASTM E104?

ASTM E104, Standard Practice for Maintaining Constant Relative Humidity by Means of Aqueous Solutions, describes a practical approach for producing controlled humidity environments using aqueous solutions. The standard is commonly used as a technical reference when a specific relative humidity must be maintained under defined conditions. It supports users who need a consistent method for humidity control rather than an arbitrary lab setup. As an ASTM standard, it provides a common basis for reliable practice and communication.

Where is ASTM E104 used?

ASTM E104 is commonly used in laboratories, quality control settings, and test environments where relative humidity must be kept steady with aqueous solution systems. It may support conditioning of materials, comparison testing, or other procedures that depend on controlled moisture exposure. The standard is useful wherever a repeatable humidity level is needed for evaluation or storage-related testing. For organizations working with sensitive products or materials, ASTM E104 helps align the setup with a recognized technical practice.

Why is ASTM E104 important?

ASTM E104 is important because controlled humidity can strongly affect test outcomes, material behavior, and conditioning results. Using a recognized practice helps improve consistency across facilities and reduces variation in humidity-related procedures. It also supports procurement and compliance decisions by giving buyers and users a clear technical reference. For testing and quality control, ASTM E104 can help reduce risk, improve repeatability, and make results easier to compare and document.

• Aqueous-solution humidity control
• Constant relative humidity practice
• Laboratory conditioning reference
• Testing consistency support
• Quality control application