ASTM D1640/D1640M-14(2018)

3.1 These test methods can be used to determine the various stages and rates of drying, curing, and film formation of organic coatings for comparing types of coatings, assessing the impact of compositional changes on drying time, or for assessing drying/curing time in the shop or field. Low temperature can significantly slow the drying rate of coatings so low temperature curing agents, catalysts and/or accelerators are often available to aid drying and film formation under cooler temperatures. Method B is designed to evaluate these components and/or to determine the effect of cooler temperatures on drying rates. Conversely, the drying/curing rate of certain coatings can be accelerated under elevated temperature/humidity conditions, while others may be adversely impacted by elevated humidity. Method C is designed to evaluate the effects of elevated temperature and relative humidity conditions on drying, curing, and film formation of paints and coatings. The terms dry or drying, cure or curing, and film formation are used interchangeably throughout this standard.

3.2 Test Methods A, B and C are limited to a comparison of paints/coatings applied to smooth, non-absorbent substrates and do not reflect the effect of absorption of the paint vehicle into the substrate material.

1.1 These test methods cover the determination of the various stages and rates of film formation in the drying or curing of organic coatings under laboratory controlled conditions of air temperature, (low, ambient and/or elevated) and/or humidity. Procedures for assessing drying under prevailing conditions of temperature and humidity in the shop and field are also described.

1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.

1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.