ASTM D779
Standard Test Method for Determining the Water Vapor Resistance of Sheet Materials in Contact with Liquid Water by the Dry Indicator Method
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About This Item
ASTM D779 is the standard test method for determining the water vapor resistance of sheet materials in contact with liquid water by the dry indicator method. It provides a consistent way to evaluate how a sheet material behaves when exposed to moisture from one side and liquid water on the other. For product selection, performance comparison, and quality control, this type of testing can help support more reliable decisions about moisture-related performance.
What is ASTM D779?
ASTM D779 defines a test method focused on water vapor resistance in sheet materials under contact with liquid water, using a dry indicator approach. The standard is intended to give a repeatable technical basis for measuring how materials restrict vapor transmission in this specific condition. As an ASTM standard, it is commonly used as a reference for laboratory testing, specification work, and product evaluation where moisture resistance is a relevant performance factor. The designation helps identify the exact method being applied.
Where is ASTM D779 used?
This standard is typically used in laboratories, materials testing programs, and procurement workflows that evaluate sheet materials exposed to moisture or liquid water contact. It may be relevant for products where vapor resistance is part of the performance profile, such as barrier-type sheets, liners, or similar flat materials. ASTM D779 is also useful when comparing test results across suppliers or verifying that a material meets a defined technical requirement within a specification or quality control process.
Why is ASTM D779 important?
ASTM D779 matters because it supports consistent measurement of a moisture-related property that can affect product performance and service life. Using a recognized test method helps reduce ambiguity in reporting, specification review, and supplier comparisons. It can also improve confidence in compliance decisions by providing a repeatable approach for evaluating resistance to water vapor under liquid-water contact conditions. For engineering and quality teams, that consistency is valuable when assessing material suitability and reducing product risk.
- Water vapor resistance testing
- Dry indicator method
- Sheet material evaluation
- Liquid water contact conditions
- Quality control and specification support
- Publication Date: 2022-10-06
- Publisher: ASTM
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