ASTM D1653:13(R2021) pdf free download – Standard Test Methods for Water Vapor Transmission of Organic Coating Films.
9. Test Conditions
9.1 Unless other conditions are agreed upon between the purchaser and the seller, the tests shall be perftnned under one or more of the following conditions:
9.1.1 Condithn A—Test chamber or cabinet maintained at 73° ± 1°F (23 ± 0.6°C) and 50 ± 2 % relative humidity.
9.1.2 condition B—Test chamber or desiccator maintained at 100 ± 1°F (38 ± 0.6°C) and 90 ± 2% relative humidity.
10. Procedure
10.1 Prepare at least three penn cups or dishes for each test material as follows:
10.1.1 Fill the cups with desiccant to within ¼ in. (6 mm) of the top edge.
10.1.2 lIthe cups are equipped with flanges. place the test specimen between the flanges and adjust the clamps to hold it firmly in position.
10.1.3 II the cups are not equipped with flanges, seal the test specimen to the top edge of the cups with wax as follows:
10.1,3.1 First carefully place the test specimen, cut to the size of the frame, on a thin cardboard ring soaked in molten wax.
10.1.3.2 Then place the specimen-covered frame over the mouth of the cup. Thoroughly seal the frame to the edge of the cup at the temperature to be used in the test. If the coating is on a substrate or support, place the coated side away from the desiccant in the cup.
Note 5—Imperfections in the film thai are nut readily visible may produce inconsistent results: consequently make sure that the lest is always run at least in triplicate.
10.2 Weigh the loaded cups to I mg and if a test chamber is not being used, place them in the test cabinets or desiccators. Record time, temperature, and relative humidity.
10.3 Remove if necessary, the cups for periodic weighing to determine weight gain. Coatings expected to have high WVT rulings, over 10 pcrms. may require weighings more frequently than once a day.
10.4 In general. weigh the cups every 24 h for a period of 3 weeks, or until the weight change versus time becomes constant. Record the time that weighings are taken to the precision of approximately I of the time span between weighings. Thus. if weighings are made every day. atime to the nearest 15 minutes would he allowed.
10.5 Shake cups containing desiccant everyday In prevent surface saturation of the material. If moisture absorbed by the desiccant exceeds 20 % of the desiccant weight. discontinue the test.
10.6 Return the cups to the test chamber immediately after weighing.
TFST METHOL) B—WET CUP METHOD 11. Test Conditions
11.1 Unless other conditions are agreed upon between the purchaser and the seller, perform the test(s) under one or more of the following conditions.