ASTM D1653-93(1999)e1

NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
e1
Designation: D 1653 – 93 (Reapproved 1999)
Standard Test Methods for
Water Vapor Transmission of Organic Coating Films
This standard is issued under the fixed designation D 1653; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
e NOTE—Editorially changes made throughout in December 1999.
1. Scope 3.1.1 water vapor transmission rate, WVT—the steady wa-
ter vapor flow in unit time through unit area of a body, between
1.1 These test methods cover the determination of the rate at
two specific parallel surfaces, under specific conditions of
which water vapor passes through films of paint, varnish,
temperature and humidity at each surface. Accepted inch-
lacquer, and other organic coatings. The films may be free films
pound unit is grains per square foot per hour. Accepted SI unit
or they may be applied to porous substrates.
is grams per square metre per 24 h.
1.2 Two test methods are covered as follows:
3.1.2 water vapor permeance, WVP—the steady water va-
1.2.1 Test Method A—Dry Cup Method, and
por flow in unit time through unit area of a body (WVT)
1.2.2 Test Method B—Wet Cup Method.
induced by unit vapor pressure difference (Dp) between the two
1.2.3 Agreement should not be expected between results
surfaces of a coating. Therefore, WVP 5 WVT/D p. Accepted
obtained by different methods or test conditions. The method
inch-pound unit is grains per square foot per hour per inch of
that most closely approaches the conditions of use should be
mercury (called a perm). Accepted SI unit is grams per square
selected.
metre per 24 h per millimetre of mercury (called a metric
1.3 The values stated in inch-pound units are to be desig-
perm).
nated as the standard. Factors for conversion are stated in
13.2.1.2 and 13.2.2.2.
4. Summary of Test Methods
1.4 This standard does not purport to address the safety
4.1 In Test Method A (Dry Cup Method), the test specimen
concerns, if any, associated with its use. It is the responsibility
is sealed to the open mouth of a cup or dish containing
of the user of this standard to establish appropriate safety and
desiccant, and the assembly placed in a test chamber with a
health practices and determine the applicability of regulatory
controlled atmosphere. Two sets of exposure conditions are
limitations prior to use.
acceptable for this test method.
2. Referenced Documents 4.1.1 Condition A, consisting of 50 % relative humidity at
73°F (23°C), and
2.1 ASTM Standards:
4.1.2 Condition B, consisting of 90 % relative humidity at
D 823 Practices for Producing Films of Uniform Thickness
100°F (38°C).
of Paint, Varnish, and Related Products on Test Panels
4.2 In Test Method B (Wet Cup Method), the test specimen
D 1005 Test Methods for Measurement of Dry-Film Thick-
is sealed to the open mouth of a cup or dish containing water,
ness of Organic Coatings Using Micrometers
3 and the assembly placed in a test chamber with a controlled
D 1193 Specification for Reagent Water
atmosphere. Two sets of exposure conditions are acceptable for
D 4708 Practice for Preparation of Free Films of Organic
2 this test method:
Coatings
4.2.1 Condition A, consisting of 50 % relative humidity at
E 104 Practice for Maintaining Constant Relative Humidity
4 73°F (23°C), and
by Means of Aqueous Solutions
4.2.2 Condition C, consisting of very low (near zero)
3. Terminology relative humidity at 73°F (23°C).
4.3 In both methods, periodic weighings of the cup or dish
3.1 Definitions of Terms Specific to This Standard:
are made to determine the rate of water vapor movement
through the specimen.
These test methods are under the jurisdiction of ASTM Committee D-1 on Paint
and Related Coatings, Materials, and Applications and are the direct responsibility
5. Significance and Use
of Subcommittee D01.23 on Physical Properties of Applied Paint Films.
Current edition approved Dec. 15, 1993. Published February 1994. Originally
5.1 One of the factors affecting the performance provided
published as D 1653 – 59 T. Last previous edition D 1653 – 91a.
2 by an organic coating is its capability of resisting or aiding the
Annual Book of ASTM Standards, Vol 06.01.
Annual Book of ASTM Standards, Vol 11.01. passage of water vapor. In some services, for example, exterior
Annual Book of ASTM Standards, Vol 11.03.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 1653
wood and masonry, the coating has to allow moderate amounts to Type IV of Specification D 1193.
of water vapor to pass through the film without damage to it. 7.2 Desiccant, consisting of either anhydrous calcium chlo-
Hence, the water vapor transmission characteristics of coatings ride (CaCL ) or anhydrous magnesium perchlorate (Mg-
are important in assessing their performance in practical use. (CLO ) ). The calcium chloride should be dried at 400°F
4 2
5.2 The purpose of these test methods is to obtain values of (200°C) before use. If calcium chloride will react with the test
water vapor transfer through coatings that range in permeabil- specimen, an adsorbing desiccant such as a silica gel may be
ity from high to low. These values are for use in design, used but the moisture gain by this desiccant during the test
manufacture, and marketing. must be limited to 4 %. Use caution in handling magnesium
5.3 The water vapor transmission is not a linear function of perchlorate because of possible chemical reaction that may be
film thickness, temperature or relative humidity. produced if it comes in contact with some organic materials
5.4 Values of water vapor transmission rate (WVT) and and is subsequently heated to regenerate the anhydrous salt.
water vapor permeance (WVP) can be used in the relative 7.3 Sealant, such as wax for attaching the test specimen to
rating of coatings only if the coatings are tested under the same the top of the perm cup or dish. It must be highly resistant to
closely controlled conditions of temperature and relative hu- the passage of water vapor. It must not lose weight to, or gain
midity, and if their thicknesses are equal. weight from, the atmosphere in an amount, over the required
5.5 Test Method A—The Dry Cup Method is the preferred period of time, that would affect the test results by more than
test method for obtaining values that relate to conventional 2 %. It must not affect the vapor pressure in a water-filled dish.
dwellings where high relative humidities are not anticipated.
NOTE 1—Among acceptable sealants are (1) a 60:40 mixture of
5.6 Test Method B—The Wet Cup Method is the preferred
microcrystalline wax and refined crystalline parafin wax, ( 2) tissue
test method for obtaining values that relate to applications
embedding wax, and (3) a 50:50 mixture of beeswax and rosin.
where high relative humidities are anticipated in the vicinity of
7.4 Release Paper, prepare free films, whenever possible to
the barrier material. In general, the more permeable a coating
eliminate the potential interference of substrates, on release
is to the passage of moisture as is typical of many water-
paper or glass substrates following procedures outlined in
reducible coatings, the greater its affinity for water and the
Practice D 4708.
greater the increase in transmission when tested in and exposed
7.5 Film Support, for preparing films that are too brittle or
to high humidities. Absorption of water may make a coating
otherwise unsatisfactory for handling as free films. Support
less dense, thus allowing moisture to diffuse easily and cause a
materials such as paper charts, filter paper, and glass cloth
much higher moisture vapor transmission rate, (WVTR) than
have been found satisfactory in some instances. Such support
would occur in drier environments.
can have an effect on the test results.
6. Apparatus
8. Test Specimens
6.1 Perm Cup or Dish, consisting of a container made of a
8.1 It is very important that the test specimens be smooth,
noncorroding material, impermeable to water or water vapor. If
and completely continuous films of uniform thickness through-
the cup or dish is made of aluminum, it must be anodized or
out the test area. Apply air drying coatings to substrates using
given a protective clear coating to prevent corrosion.
one of the methods described in Practices D 823 or D 4708.
6.1.1 One type of cup that is suitable has a flanged edge and
NOTE 2—Special test conditions may require that the coating be applied
is equipped with a separate corresponding flange, so that the
by brushing, roller coating or other special methods. The thickness of the
test specimen can be held between them. The contacting faces
coating applied shall be within normal range for the type of material under
of the flanges shall be ground to such flatness that when the
test, and shall not vary by more than 5 % of the total thickness in any test
film is in position, moisture transfer can occur only through the series.
NOTE 3—When applying baking finishes, bake for specified time and
exposed film area. For hard films, or films having a very rough
temperature in accordance with manufacturers’ instructions. Permeance
surface, a soft rubber gasket may be inserted between the film
may vary with the baking schedule or the time of air drying.
and the flange. The flanges shall then be held together with
8.2 Air dry the coated material in a horizontal position for 7
suitable clamps.
days in a room preferably maintained at 73.5 6 3.5°F (236
6.1.2 Another suitable cup is any open circular or rectangu-
2°C) and 50 6 5 % relative humidity. If the material is to be
lar dish to which the test film can be sealed with wax or sealant.
tested as a free film, remove it from the substrate and allow the
6.2 Test Chamber, with a controlled temperature and rela-
previously unexposed surface to dry for an additional 7 days.
tive humidity as specified in Section 4. Air shall be circulated
The drying schedule may be modified as recommended by
throughout the chamber to maintain uniform conditions at all
manufacturer.
test locations. For low or high humidity conditions, a standard
desiccator or other suitable cabinet may be used. For maintain-
The sole source of supply of release Paper, Form RP-1K, known to the
ing constant relative humidity by means of aqueous solutions,
committee at this time is the Leneta Co., 15 Whitney Rd., Mahwah, NJ 07430 . If
refer to procedures outlined in Practice E 104.
you are aware of alternative suppliers, please provide this information to ASTM
6.3 Analytical Balance, having an adequate capacity for the
Headquarters. Your comments will receive careful consideration at a meeting of the
weight of the test cups and a sensitivity of 1 mg. responsi ble technical committee, which you may attend.
The sole source of supply of paper charts, Form NWK, known to the committee
at this time is the Leneta Co., 15 Whitney Rd., Mahwah, NJ 07430 . If you are aware
7. Reagents and Materials
of alternative suppliers, please provide this information to ASTM Headquarters.
7.1 Purity of Water—Unless otherwise indicated, reference
Your comments will receive careful consideration at a meeting of the responsi ble
to water shall be understood to mean reagent water conforming technical committee, which you may attend.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 1653
NOTE 4—Examine test films for the presence of pinholes or other
10.5 Shake cups containing desiccant everyday to prevent
defects before commencing the test. It may be advisable to apply the test
surface saturation of the material. If moisture absorbed by the
material in two coats, applying the second coat perpendicular to the first
desiccant exceeds 20 % of the desiccant weight, discontinue
coat and allowing for an adequate drying period between coats to achieve
the test.
the desired film thickness.
10.6 Return the cups to the test chamber immediately after
8.3 Measure the thickness of the test specimen in several
weighing.
places with a micrometer using procedures in Test Methods
D 1005 to ensure a uniform thickness.
TEST METHOD B—WET CUP METHOD
8.4 When coatings are applied to support materials, the
coated side of the test specimen should be placed away from
11. Test Conditions
the desiccant or towards the water in the cup, depending upon
11.1 Unless other conditions are agreed upon between the
the service environment. Coatings should not be applied to
purchaser and the seller, perform the test(s) under one or more
both sides of a support. Glass cloth is preferred for coatings
of the following conditions:
that are cured by baking.
11.1.1 Condition A—Test chamber or cabinet maintained at
TEST METHOD A—DRY CUP METHOD
73 6 1°F (23 6 0.6°C) and 50 6 2 % relative humidity.
11.1.2 Condition C—Test chamber or desiccator maintained
9. Test Conditions
at 73 6 1°F and very low (near zero) relative humidity.
9.1 Unless other conditions are agreed upon between the
purchaser and the seller, the tests shall be performed under one
12. Procedure
or more of the following conditions:
12.1 Prepare at least three cups for each test material as
9.1.1 Condition A—Test chamber or cabinet maintained at
follows:
73° 6 1°F (23 6 0.6°C) and 50 6 2 % relative humidity.
12.1.1 Fill the cups with water to within ⁄4 in. (6 mm) of the
9.1.2 Condition B—Test chamber or desiccator maintained
top edge.
at 100 6 1°F (38 6 0.6°C) and 90 6 2 % relative humidity.
12.1.2 If the cups are equipped with flanges, place the test
10. Procedure
specimen over the opening of the cups between the flanges and
adjust the clamps to hold them firmly in position. If the coating
10.1 Prepare at least three perm cups or dishes for each test
material as follows: is on a substrate or support, place the coated side towards the
water in the cups.
10.1.1 Fill the cups with desiccant to within ⁄4 in. (6 mm) of
the top edge. 12.1.3 If the cups are not equipped with flanges, seal the test
10.1.2 If the cups are equipped with flanges, place the test specimens to the top edge of the cups with wax in accordance
specimen between the flanges and adjust the clamps to hold it with procedures in 10.1.3.1 and 10.1.3.2. If the coating is on a
firmly in position. substrate or support, place the coa
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