ASTM D7233-08(2017)

Standard Test Method for Testing Fracture of Level Paintbrush Filaments

SIGNIFICANCE AND USE
3.1 This method is intended to evaluate filaments for suitability of use in paintbrushes prior to manufacture. Filament fracture resistance is very important because paintbrushes are bent or flexed during painting and it is necessary that the filaments are not permanently deformed with usage.
SCOPE
1.1 This test method covers a procedure for determining the number of fractures present when paintbrush filaments are bent.  
1.2 This method is applicable only to monofilaments with consistent longitudinal cross sectional dimensions commonly referred to as “level” filaments.  
1.3 The values derived are in percent fractured filaments. For example, 2 fractured out of 18 filaments tested = 2/18 or 11 %.  
1.4 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.  
1.5 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 and health practices and determine the applicability of regulatory limitations prior to use.  
1.6 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-May-2017
• ICS: 87.100 - Paint coating equipment
• Technical Committee: D01 - Paint and Related Coatings, Materials, and Applications
• Drafting Committee: D01.61 - Paint Application Tools

Relations

• Replaces: ASTM D7233-08(2012) - Standard Test Method for Testing Fracture of Level Paintbrush Filaments
• Effective Date: 01-Jun-2017

Overview

ASTM D7233-08(2017) is a standard test method developed by ASTM International for assessing fracture resistance in level paintbrush filaments. This test is crucial for determining whether paintbrush filaments are suitable for use prior to manufacturing, ensuring durability and performance during painting. The procedure is specifically intended for "level" monofilaments, which have consistent longitudinal cross-sectional dimensions, and evaluates their ability to withstand repeated bending and flexing without permanent deformation or fracturing.

Key Topics

• Fracture Resistance: The standard focuses on the ability of paintbrush filaments to resist breaking or permanent kinking during flexing - a typical stress experienced during regular painting use.
• Applicability: This test method applies exclusively to level monofilaments used in paintbrushes, not other brush types or filament forms.
• Measurement Methodology:
  • Filaments are bent to a specified displacement using a calibrated gauge.
  • Each filament is visually inspected for cracks, permanent deformation, or fractures.
  • Results are reported as the percentage of fractured filaments out of the total tested (e.g., 2 out of 18 filaments = 11%).
• Testing Conditions: Results can be influenced by conditions such as temperature and humidity, as well as filament characteristics like cross-sectional shape and polymer type.
• Precision: The standard includes guidelines for repeatability and reproducibility based on interlaboratory testing, providing confidence in the comparability of results.

Applications

ASTM D7233-08(2017) is widely used in the paintbrush and coatings industry to:

• Quality Control: Manufacturers use this standard during the quality assurance phase to screen batches of filaments before paintbrush production, ensuring only filaments with sufficient fracture resistance are used.
• Material Comparison: The method helps compare different filament types, polymers, and processing methods for optimal paintbrush performance.
• Product Development: R&D teams employ the test method to innovate new filament materials or designs with improved fracture resistance for premium brushes.
• Specification Compliance: The standard helps suppliers and buyers verify that supplied filaments meet predefined performance criteria, supporting contractual and regulatory requirements.
• Industry Consistency: By relying on a standardized procedure, the industry ensures consistency, reliability, and safety, reducing variability and increasing consumer satisfaction.

Related Standards

• ASTM D01 Series: Standards for paints, related coatings, materials, and application tools.
• ISO Standards: Various international test methods for evaluating filament and fiber durability.
• Other ASTM Filament Testing Standards: For characteristics such as tensile strength, flexibility, or chemical resistance.

ASTM D7233-08(2017) aligns with international standardization principles recognized by the World Trade Organization’s TBT Committee. Following this test method supports harmonized manufacturing, international trade, and regulatory compliance in the paint application tools sector.

For additional information, users should always refer to the latest version of the standard and follow all safety and handling instructions specified by ASTM International.

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: D7233 − 08 (Reapproved 2017)
Standard Test Method for
Testing Fracture of Level Paintbrush Filaments
This standard is issued under the fixed designation D7233; 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 fracture resistance is very important because paintbrushes are
bent or flexed during painting and it is necessary that the
1.1 This test method covers a procedure for determining the
filaments are not permanently deformed with usage.
number of fractures present when paintbrush filaments are
bent.
4. Apparatus
1.2 This method is applicable only to monofilaments with
4.1 The apparatus for this method is shown in Fig. 3.
consistent longitudinal cross sectional dimensions commonly
Filaments are secured between two clamps. The handwheel on
referred to as “level” filaments.
the front of the gauge is rotated to bring the ends of the
1.3 The values derived are in percent fractured filaments.
filaments toward each other as measured by the dial indicator
For example, 2 fractured out of 18 filaments tested = ⁄18 or
at the top of the gauge.
11 %.
4.2 Thedeviceisverydelicateandcareshouldbeusedinits
1.4 The values stated in inch-pound units are to be regarded
operation. To prevent instrument damage, the clamps must not
as standard. The values given in parentheses are mathematical
be brought together closer than a reading of 0.750 in. (19.0
conversions to SI units that are provided for information only
mm) on the dial indicator.
and are not considered standard.
5. Sampling, Test Specimens and Test Units
1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
5.1 Record the polymer type, filament size and filament
responsibility of the user of this standard to establish appro- cross-sectional shape.
priate safety and health practices and determine the applica-
5.2 The sample filaments shall be conditioned for one (1) h
bility of regulatory limitations prior to use.
at73.5 63.5°F(23.0 62.0°C)and50 65 %relativehumidity.
1.6 This international standard was developed in accor-
5.3 The sample filaments shall be cut to a minimum of 1.5
dance with internationally recognized principles on standard-
in. (38.1 mm).
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
5.4 Thedistancebetweenclampsonthetestunitshallbe1.0
mendations issued by the World Trade Organization Technical
in.(25.4mm)atareadingof0.0(zerodeflection).(SeeFig.4.)
Barriers to Trade (TBT) Committee.
6. Procedure
2. Summary of Test Method
6.1 Select three distinct sections of the bundle, box or lot of
2.1 Filaments are clamped in place and bent to a specific
filaments to be evaluated. Do not include filaments from the
displacement. While bent and still in the fixture, they are
perimeter of a bundle. Pull six (6) filaments from each section
evaluated for fracture by visually determining whether the
at equally dispersed intervals.
filamentshavecrackedorbeenpermanentlydeformedandwill
6.2 Set the clamps in a parallel horizontal position with the
not recover to virtually straight filaments. (See Fig. 1 and Fig.
dial indicator set at 0.0 (zero deflection). (See Fig. 4.)
2).
6.3 Place the six (6) filaments in the clamps. Be sure that no
3. Significance and Use
filamentoverlapsorisontopofanotherfilament.Closeclamps
3.1 This method is intended to evaluate filaments for suit-
to secure.
ability of use in paintbrushes prior to manufacture. Filament
1 2
This test method is under the jurisdiction of ASTM Committee D01 on Paint The sole source of supply of the assembled fracture gauge test device known to
and Related Coatings, Materials, andApplications and is the direct responsibility of the committee at this time is T. S. Simms and Co., 33 Bridge Rd.,
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