ASTM D6686-01

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Designation:D6686–01
Standard Test Method for
Evaluation of Tannin Stain Resistance of Coatings
This standard is issued under the fixed designation D 6686; 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.
1. Scope and to a lesser degree in white and yellow pine. Tannins are
alsopresentinvaryingamountsinwoodcompositionproducts.
1.1 This test method is an accelerated procedure to deter-
These extractives are solubilized and darkened in color by
mine the effectiveness of latex coatings at preventing the
aqueous coatings, resulting in unsightly yellow or brown
migration of tannin stains from wood substrates.
discolorations. This test method is designed to show the
1.2 The values in SI units are to be regarded as the standard.
relative ability of paints to prevent tannin bleed-through.
The values in parenthesis are for information only.
Typically cedar or redwood panels are used for this test.
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
6. Apparatus
responsibility of the user of this standard to establish appro-
6.1 Test Chamber, as described in Practice D 4585.
priate safety and health practices and determine the applica-
6.2 Test Substrate, 2.4 by 19.2 cm (6 by 48 in.) substrate or
bility of regulatory limitations prior to use.
of a size agreed upon by the purchaser and seller of the coating
2. Referenced Documents being tested.
6.3 Paint Brush, nylon/polyester brush of good quality.
2.1 ASTM Standards:
6.4 Spectrophotometer.
D 1475 Test Method For Density of Liquid Coatings, Inks,
2 6.5 Electronic Balance.
and Related Products
6.6 Conditioned Room, at 18 to 29.5°C (65 to 85°F) and 40
D 4585 Practice for Testing Water Resistance of Coatings
2 to 60 % relative humidity.
Using Controlled Condensation
D 5068 Practice for Preparation of Paint Brushes for Evalu-
7. Reagents and Materials
ation
7.1 Wood Panels—Such as cedar, redwood, oak, white pine,
3. Terminology yellow pine or other substrate as agreed upon between the
purchaser and the seller of the coating being tested.
3.1 Definitions:
7.2 Control Paint—An agreed-upon paint of known tannin
3.1.1 tannin stain resistance—the ability of a coating to
stain resistance.
prevent the migration of tannins or other wood-based chro-
7.3 Test Paints—Since there are no standard panels, photo-
mophores to the surface of a film.
graphs, or paints for this test method, an agreed-upon control
4. Summary of Test Method
paint (7.2) should be included as one of the test paints.
4.1 This test method utilizes a condensation test chamber to
8. Procedure
determine the tannin stain resistance of latex paints. The test
8.1 Choose a substrate with a consistent grain pattern.
paints are applied to substrates that contain tannin extractives
Patterns vary greatly from panel to panel, so try to select a
and are placed on or in the test chamber. CIELAB L* and b*
board that has consistent wood grain across the length of the
valuesaswellassubjectiveratingsarerecordedafterexposure.
substrate. Results may vary from panel to panel because of
5. Significance and Use different growth rates, grain angles, colors and species of
wood. If necessary, panels may be sanded to remove raised
5.1 Tannins and other chromophoric extractives are natu-
grain. Substrates with areas of rough spots should be avoided,
rally occurring materials in wood and wood-based substrates.
as they will bleed through more readily. Divide substrate into
Tannins are prevalent to a high degree in cedar, redwood, oak
stripsatleast2.4cm(6in.)wideorasagreeduponbetweenthe
purchaser and the seller and label the back of each test area
This test method is under the jurisdiction of ASTM Committee D01 on Paint
with paint designation.The control paint should be placed near
and Related Coatings, Materials, and Applictions and is the direct responsibility of
the middle of the panel.
Subcommittee D01.42 on Architectural Coatings.
8.2 Prepare the cabinet as described in Practice D 4585.
Current edition approved June 10, 2001. Published August 2001.
Annual Book of ASTM Standards, Vol 06.01.
Annual Book of ASTM Standards, Vol 06.02.
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D6686
8.3 Prepare paint brush as described in Practice D 5068. sure panels are placed at an angle to avoid water spotting and
8.4 Prime all edges of the panels with an appropriate primer run off onto the test areas.
8.7 Adjust the thermostat to maintain the desired tempera-
and allow to dry according to manufacturer’s recommenda-
tions. The backside of the panels must also be primed if the ture of the saturated air and water vapor mixture. Ca
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