ASTM D and ASTM E96 both address the determination of the water vapor transmission and permeance of coatings. ASTM E96/E96M. ASTM D Standard Test Methods for Water Vapor Transmission of Organic Coating Films. Buy ASTM D R TEST METHODS FOR WATER VAPOR TRANSMISSION OF ORGANIC COATING FILMS from SAI Global.
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The Water Vapor Permeance is often simply call the permeance, and the water vapor permeability is often simply called the permeability. If the container is filled with desiccant, the method is called the dry cup method or the desiccant method.
It c1653 be used to test paper, plastic films, other sheet materials, fiberboards, gypsum and plaster products, wood products, and plastics. Your email address will not be published.
Leave this field empty. Water vapor is the gaseous phase of water. ASTM E96 covers many materials, including coatings. Referenced Documents purchase separately The documents listed below are referenced within the subject standard but are not provided as part of the standard.
Otherwise blistering and peeling will likely occur. Leave a Reply Cancel reply Your email address will not be published. Water vapor can be produced by the evaporation of water or the sublimation of ice or snow.
The Significance of the Permeability of Paints
The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard. For the wet cup method, two results, each the mean of triplicate trials, are expected to differ by less than It can also be produced by the boiling of water, but the steam that you can see coming out of your kettle technically is not water vapor.
They run essentially the same kinds of tests as in the ASTM methods, but do so instrumentally.
In general, the more permeable a coating is to the passage of moisture as is typical of many water-reducible coatings, the greater its affinity for water and the greater the increase in transmission when tested in and exposed to high humidities. What is water vapor? The repeatability values reported by these two ASTM standards indicate the permeance values determined dd1653 ball park figures.
Finally, be cautious when comparing the results obtained by the dry cup method to the wet cup methods.
ASTM D – 13 Standard Test Methods for Water Vapor Transmission of Organic Coating Films
In some services, for example, exterior wood and masonry, the coating has to allow moderate amounts of water vapor to pass through the film zstm damage to it.
It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
What are ashm formulas and units for WVT, permeance, and permeability? The films may be free films or they may be applied to porous substrates. Historical Version s – view previous versions of standard.
The Significance of the Permeability of Paints | KTA UniversityKTA University
In the gas phase, water molecules move very rapidly and are not bound together. This correction can greatly change the results. ASTM D covers the evaluations of films of coatings: The Water Vapor Transmission WVTpermeance, and permeability are very closely related in that one is calculated from the other. Temperature and Relative Humidity Testing Standard: First the WVT is determined.
The fundamentals of the measurement of water vapor transmission in the laboratory are simple.
All paint and coatings are permeable to water, just to different degrees. If the cup contains desiccant, the dish satm water weight over the course of the test, so the plot points upward. The wet cup method can produce higher results than the dry cup method when the same coating is tested under the same air temperature and d1635 conditions.
However, it appears that no side-by-side tests have been run comparing results from measurements with such instruments to these ASTM methods for precision and accuracy. WVT is determined by sealing a free film of the test material to the top of a container that is filled with water left or desiccant right.