ASTM D3258-04(2019)

Standard Test Method for Porosity of White or Near White Paint Films by Staining

ABSTRACT
This test method details the standard procedure for determining the porosity of white or near white mineral spirits insoluble paint film by staining to indicate the degree to which a subsequent coat will penetrate. This test method shall require the use of film applicators, reflectometer, vacuum drawdown plate, camelhair brush, plastic wash bottle, test panel, penetrating medium, and filter paper. The test paint is applied to a nonporous surface, air dried, then measured for reflectance. A special colored penetrating medium is applied, the excess removed in a specified manner, and reflectance measured again. The difference between the two readings indicates the degree of porosity; the smaller the difference, the lower the porosity of the film and the greater its ability to resist penetration.
SCOPE
1.1 This test method covers the determination of the porosity of a white or near white mineral spirits insoluble paint film to indicate the degree to which a subsequent coat will penetrate.  
1.2 The texture of the film can affect cleanup that will influence the results of the test. A stain applied to a high-hiding paint will not lower the reflectance as much as the same stain applied to a low-hiding paint of equal porosity. These points must be considered in comparing different paints.  
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.  
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-Mar-2019
• ICS: 87.040 - Paints and varnishes
• Technical Committee: D01 - Paint and Related Coatings, Materials, and Applications
• Drafting Committee: D01.42 - Architectural Coatings

Relations

• Replaces: ASTM D3258-04(2014) - Standard Test Method for Porosity of White or Near White Paint Films by Staining
• Effective Date: 01-Apr-2019
• Refers: ASTM E1347-06(2020) - Standard Test Method for Color and Color-Difference Measurement by Tristimulus Colorimetry
• Effective Date: 01-May-2020
• Refers: ASTM E1347-06(2015) - Standard Test Method for Color and Color-Difference Measurement by Tristimulus Colorimetry
• Effective Date: 01-Nov-2015
• Refers: ASTM E1347-06(2011) - Standard Test Method for Color and Color-Difference Measurement by Tristimulus Colorimetry
• Effective Date: 01-Nov-2011
• Refers: ASTM E1347-06 - Standard Test Method for Color and Color-Difference Measurement by Tristimulus Colorimetry
• Effective Date: 01-Dec-2006
• Refers: ASTM E1347-03 - Standard Test Method for Color and Color-Difference Measurement by Tristimulus (Filter) Colorimetry
• Effective Date: 10-Jul-2003
• Refers: ASTM E1347-97 - Standard Test Method for Color and Color-Difference Measurement by Tristimulus (Filter) Colorimetry
• Effective Date: 10-Jun-1997
• Referred By: ASTM D5324-16(2022) - Standard Guide for Testing Water-Borne Architectural Coatings
• Effective Date: 01-Apr-2019
• Referred By: ASTM D6583-13(2019) - Standard Test Method for Porosity of Paint Film by Mineral Oil Absorption
• Effective Date: 01-Apr-2019

Overview

ASTM D3258-04(2019), titled Standard Test Method for Porosity of White or Near White Paint Films by Staining, sets out a widely recognized procedure for assessing the porosity of white or near-white, mineral spirits-insoluble paint films. Developed by ASTM International, this test method uses staining techniques and reflectance measurements to evaluate how much a subsequent coat might penetrate an existing paint film. This information is essential for understanding film quality and predicting paint performance in various applications.

Porosity is a key characteristic impacting the durability, covering ability, and protective function of paint films. Accurate and consistent assessment of porosity supports product quality control, specification compliance, and effective material comparisons in architectural, industrial, and laboratory environments.

Key Topics

• Purpose of the Test: This standard outlines a method to determine the porosity of certain paint films, indicating the likelihood of a subsequent coating penetrating the surface.
• Test Method Summary:
  • Paint is applied to a nonporous test panel and air dried.
  • Reflectance is measured before and after application of a colored penetrating medium.
  • The change in reflectance quantifies porosity: a smaller difference means lower porosity and better resistance to penetration.
• Influencing Factors: The texture and hiding power of the paint film can affect stain cleanup and reflectance measurements, making it important to consider these aspects when comparing different products.
• Required Equipment:
  • Film applicators of specified widths and clearances
  • Reflectometer (per ASTM E1347)
  • Vacuum drawdown plate
  • Camelhair brush and plastic wash bottle
  • Nonporous sealed panel (e.g., white plastic or cardboard)
  • Penetrating medium with dye and pigment
  • Filter paper
• Data Reporting and Precision: The standard specifies how to report results and sets repeatability and reproducibility benchmarks for quality assurance.

Applications

The practical value of ASTM D3258-04(2019) extends across multiple fields, including:

• Quality Control in Paint Manufacturing: By measuring paint film porosity, manufacturers can ensure products meet performance specifications for resistance, coverage, and durability.
• Comparative Product Evaluation: Enables laboratories and users to compare different white or near-white paint systems for their ability to resist penetration by future coats, facilitating informed selection and specification.
• Architectural and Industrial Coating Systems: Assists architects, engineers, and contractors in choosing coatings best suited for their intended application, especially where multi-layer systems are specified.
• Research and Development: Supports the development of new paint formulations with targeted porosity characteristics to enhance performance or meet specific use scenarios.
• Regulatory and Standards Compliance: Provides a standardized basis for meeting international, national, or project-specific requirements related to paint film integrity and protective qualities.

Related Standards

For a comprehensive assessment of paint films and complementary properties, consider referencing the following standards in conjunction with ASTM D3258-04(2019):

• ASTM E1347: Test Method for Color and Color-Difference Measurement by Tristimulus Colorimetry, which provides requirements for reflectometer devices used in porosity assessment.
• Other ASTM D01 Standards: Cover a variety of properties and test methods for paints, coatings, and related materials, supporting a holistic approach to quality and performance evaluation.
• ISO and Regional Standards: Where applicable, compare with ISO or local standards for paint film porosity to ensure broad compliance and market acceptance.

Keywords: ASTM D3258, paint film porosity, white paint testing, stain method, reflectance measurement, coating penetration, paint quality control, architectural coatings, industrial coatings, standard test methods.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D3258 − 04 (Reapproved 2019)
Standard Test Method for
Porosity of White or Near White Paint Films by Staining
This standard is issued under the fixed designation D3258; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope etrating medium is applied, the excess removed in a specified
manner, and reflectance measured again. The difference be-
1.1 This test method covers the determination of the poros-
tween the two readings indicates the degree of porosity; the
ity of a white or near white mineral spirits insoluble paint film
smallerthedifference,thelowertheporosityofthefilmandthe
to indicate the degree to which a subsequent coat will pen-
greater its ability to resist penetration.
etrate.
1.2 The texture of the film can affect cleanup that will
4. Apparatus and Materials
influence the results of the test.Astain applied to a high-hiding
4.1 Film Applicator, 150 mm (6 in.) wide with a clearance
paint will not lower the reflectance as much as the same stain
of 300 µm (12 mils).
applied to a low-hiding paint of equal porosity. These points
4.2 Film Applicator, 140 mm (5 ⁄2 in.) wide with a clearance
must be considered in comparing different paints.
of 250 µm (10 mils).
1.3 The values stated in SI units are to be regarded as the
4.3 Reflectometer, meeting the requirements of Test Method
standard. The values given in parentheses are for information
E1347.
only.
1.4 This standard does not purport to address all of the 4.4 Vacuum Drawdown Plate.
safety concerns, if any, associated with its use. It is the
4.5 Camelhair Brush (approximately 13 mm ( ⁄2 in.) wide).
responsibility of the user of this standard to establish appro-
4.6 Plastic Wash Bottle, containing odorless mineral spirits
priate safety, health, and environmental practices and deter-
(about 500 mL (16 oz)).
mine the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accor- 4.7 Test Panel—Smooth, nonporous panel such as sealed
dance with internationally recognized principles on standard- white, cardboard chart, or white plastic sheet.
ization established in the Decision on Principles for the
4.8 Penetrating Medium—A composition of pigment and
Development of International Standards, Guides and Recom-
dark-colored dye dispersed in organic liquid vehicle.
mendations issued by the World Trade Organization Technical
4.9 Filter Paper.
Barriers to Trade (TBT) Committee.
5. Procedure
2. Referenced Documents
5.1 Place the test panel on the vacuum plate and apply the
2.1 ASTM Standards:
paint under test with the 30-µm (12-mil) clearance drawdown
E1347 Test Method for Color and Color-Difference Mea-
blade. Remove the test panel from the vacuum plate and air dry
surement by Tristimulus Colorimetry
48 h under standard conditions of 23 6 2 °C (73 6 3.5 °F) and
3. Summary of Test Method 50 6 5 % relative humidity.
3.1 The test paint is applied to a nonporous surface, air 5.2 Determine the percent reflectance of the dry film using
dried, then measured for reflectance. A special colored pen- the green filter on the reflectometer.When making this reading,
back up the panel with a flat, rigid, opaque object and mark the
area on which the reading was made.
This test method is under the jurisdiction of ASTM Committee D01 on Paint
5.3 Place the panel containing the dry paint film on the
and Related Coatings, Materials, andApplications and is the direct responsibility of
Subcommittee D01.42 on Architectural Coatings.
vacuum plate. Using the 25-µm (10-mil) clearance blade, apply
Current edition approved April 1, 2019. Published April 2019. Originally
the penetrating medium over the test paint, covering the area
approved in 1973. Last previous editi
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