ASTM D3258-00

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D 3258 – 00
Standard Test Method for
Porosity of Paint Films
This standard is issued under the fixed designation D 3258; 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 4.2 Film Applicator,5 ⁄2 in. (140 mm) wide with a clearance
of 10 mils (250 μm).
1.1 This test method covers the determination of the poros-
4.3 Reflectometer, meeting the requirements of Test Method
ity of a white or near white mineral spirits insoluble paint film
E 97.
to indicate the degree to which a subsequent coat will pen-
4.4 Vacuum Drawdown Plate.
etrate.
4.5 Camelhair Brush (approximately ⁄2 in. (13 mm) wide).
1.2 The texture of the film can affect cleanup that will
4.6 Plastic Wash Bottle, containing odorless mineral spirits
influence the results of the test. A stain applied to a high-hiding
(about 16 oz (500 mL)).
paint will not lower the reflectance as much as the same stain
4.7 Test Panel—Smooth nonporous panel such as sealed
applied to a low-hiding paint of equal porosity. These points
white, cardboard chart, or white plastic sheet.
must be considered in comparing different paints.
4.8 Penetrating Medium—A composition of pigment and
1.3 The values stated in inch-pound units are to be regarded
dark-colored dye dispersed in organic liquid vehicle.
as the standard. The values given in parentheses are for
4.9 Filter Paper.
information only.
1.4 This standard does not purport to address all of the
5. Procedure
safety concerns, if any, associated with its use. It is the
5.1 Place the test panel on the vacuum plate and apply the
responsibility of the user of this standard to establish appro-
paint under test with the 12-mil (30-μm) clearance drawdown
priate safety and health practices and determine the applica-
blade. Remove the test panel from the vacuum plate and air dry
bility of regulatory limitations prior to use.
48 h under standard conditions of 73 6 3.5°F (23 6 2°C) and
2. Referenced Documents 50 6 5 % relative humidity.
5.2 Determine the percent reflectance of the dry film using
2.1 ASTM Standards:
the green filter on the reflectometer. When making this reading,
E 97 Test Method for Directional Reflectance Factor, 45-
back up the panel with a flat rigid opaque object and mark the
deg, 0-deg, of Opaque Specimens by Broad-Band Filter
2 area on which the reading was made.
Reflectometry
5.3 Place the panel containing the dry paint film on the
3. Summary of Test Method vacuum plate. Using the 10-mil (25-μm) clearance blade, apply
the penetrating medium over the test paint, covering the area
3.1 The test paint is applied to a nonporous surface, air
marked as above and drawing the applicator blade in the same
dried, then measured for reflectance. A special colored pen-
direction as before.
etrating medium is applied, the excess removed in a specified
5.4 After 5 min 6 15 s wash off excess penetrating
manner, and reflectance measured again. The difference be-
medium.To do this, hold the panel vertically and remove the
tween the two readings indicates the degree of porosity; the
medium using the camelhair brush wet with odorless mineral
smaller the difference, the lower the porosity of the film and the
spirits. Repeat the process until most of the excess is removed.
greater its ability to resist penetration.
Then continue to remove more of the excess by applying
4. Apparatus and Materials
mineral spirits directly from the wash bottle to the area above
the stain so that it flows across the stained area. Pause to
4.1 Film Applicator, 6 in. (150 mm) wide with a clearance
observe the bead that forms at the bottom of the panel. If the
of 12 mils (300 μm).
1 3
This test method is
...